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 verify_region_sets_optional(); 1302 1303 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1304 collector_policy()->should_clear_all_soft_refs(); 1305 1306 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1307 1308 { 1309 IsGCActiveMark x; 1310 1311 // Timing 1312 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1313 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1314 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1315 1316 { 1317 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1318 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1319 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1320 1321 double start = os::elapsedTime(); 1322 g1_policy()->record_full_collection_start(); 1323 1324 // Note: When we have a more flexible GC logging framework that 1325 // allows us to add optional attributes to a GC log record we 1326 // could consider timing and reporting how long we wait in the 1327 // following two methods. 1328 wait_while_free_regions_coming(); 1329 // If we start the compaction before the CM threads finish 1330 // scanning the root regions we might trip them over as we'll 1331 // be moving objects / updating references. So let's wait until 1332 // they are done. By telling them to abort, they should complete 1333 // early. 1334 _cm->root_regions()->abort(); 1335 _cm->root_regions()->wait_until_scan_finished(); 1336 append_secondary_free_list_if_not_empty_with_lock(); 1337 1338 gc_prologue(true); 1339 increment_total_collections(true /* full gc */); 1340 increment_old_marking_cycles_started(); 1341 1342 assert(used() == recalculate_used(), "Should be equal"); 1343 1344 verify_before_gc(); 1345 1346 pre_full_gc_dump(gc_timer); 1347 1348 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1349 1350 // Disable discovery and empty the discovered lists 1351 // for the CM ref processor. 1352 ref_processor_cm()->disable_discovery(); 1353 ref_processor_cm()->abandon_partial_discovery(); 1354 ref_processor_cm()->verify_no_references_recorded(); 1355 1356 // Abandon current iterations of concurrent marking and concurrent 1357 // refinement, if any are in progress. We have to do this before 1358 // wait_until_scan_finished() below. 1359 concurrent_mark()->abort(); 1360 1361 // Make sure we'll choose a new allocation region afterwards. 1362 release_mutator_alloc_region(); 1363 abandon_gc_alloc_regions(); 1364 g1_rem_set()->cleanupHRRS(); 1365 1366 // We should call this after we retire any currently active alloc 1367 // regions so that all the ALLOC / RETIRE events are generated 1368 // before the start GC event. 1369 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1370 1371 // We may have added regions to the current incremental collection 1372 // set between the last GC or pause and now. We need to clear the 1373 // incremental collection set and then start rebuilding it afresh 1374 // after this full GC. 1375 abandon_collection_set(g1_policy()->inc_cset_head()); 1376 g1_policy()->clear_incremental_cset(); 1377 g1_policy()->stop_incremental_cset_building(); 1378 1379 tear_down_region_sets(false /* free_list_only */); 1380 g1_policy()->set_gcs_are_young(true); 1381 1382 // See the comments in g1CollectedHeap.hpp and 1383 // G1CollectedHeap::ref_processing_init() about 1384 // how reference processing currently works in G1. 1385 1386 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1387 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1388 1389 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1390 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1391 1392 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1393 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1394 1395 // Do collection work 1396 { 1397 HandleMark hm; // Discard invalid handles created during gc 1398 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1399 } 1400 1401 assert(free_regions() == 0, "we should not have added any free regions"); 1402 rebuild_region_sets(false /* free_list_only */); 1403 1404 // Enqueue any discovered reference objects that have 1405 // not been removed from the discovered lists. 1406 ref_processor_stw()->enqueue_discovered_references(); 1407 1408 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1409 1410 MemoryService::track_memory_usage(); 1411 1412 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1413 ref_processor_stw()->verify_no_references_recorded(); 1414 1415 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1416 ClassLoaderDataGraph::purge(); 1417 MetaspaceAux::verify_metrics(); 1418 1419 // Note: since we've just done a full GC, concurrent 1420 // marking is no longer active. Therefore we need not 1421 // re-enable reference discovery for the CM ref processor. 1422 // That will be done at the start of the next marking cycle. 1423 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1424 ref_processor_cm()->verify_no_references_recorded(); 1425 1426 reset_gc_time_stamp(); 1427 // Since everything potentially moved, we will clear all remembered 1428 // sets, and clear all cards. Later we will rebuild remembered 1429 // sets. We will also reset the GC time stamps of the regions. 1430 clear_rsets_post_compaction(); 1431 check_gc_time_stamps(); 1432 1433 // Resize the heap if necessary. 1434 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1435 1436 if (_hr_printer.is_active()) { 1437 // We should do this after we potentially resize the heap so 1438 // that all the COMMIT / UNCOMMIT events are generated before 1439 // the end GC event. 1440 1441 print_hrs_post_compaction(); 1442 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1443 } 1444 1445 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1446 if (hot_card_cache->use_cache()) { 1447 hot_card_cache->reset_card_counts(); 1448 hot_card_cache->reset_hot_cache(); 1449 } 1450 1451 // Rebuild remembered sets of all regions. 1452 if (G1CollectedHeap::use_parallel_gc_threads()) { 1453 uint n_workers = 1454 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1455 workers()->active_workers(), 1456 Threads::number_of_non_daemon_threads()); 1457 assert(UseDynamicNumberOfGCThreads || 1458 n_workers == workers()->total_workers(), 1459 "If not dynamic should be using all the workers"); 1460 workers()->set_active_workers(n_workers); 1461 // Set parallel threads in the heap (_n_par_threads) only 1462 // before a parallel phase and always reset it to 0 after 1463 // the phase so that the number of parallel threads does 1464 // no get carried forward to a serial phase where there 1465 // may be code that is "possibly_parallel". 1466 set_par_threads(n_workers); 1467 1468 ParRebuildRSTask rebuild_rs_task(this); 1469 assert(check_heap_region_claim_values( 1470 HeapRegion::InitialClaimValue), "sanity check"); 1471 assert(UseDynamicNumberOfGCThreads || 1472 workers()->active_workers() == workers()->total_workers(), 1473 "Unless dynamic should use total workers"); 1474 // Use the most recent number of active workers 1475 assert(workers()->active_workers() > 0, 1476 "Active workers not properly set"); 1477 set_par_threads(workers()->active_workers()); 1478 workers()->run_task(&rebuild_rs_task); 1479 set_par_threads(0); 1480 assert(check_heap_region_claim_values( 1481 HeapRegion::RebuildRSClaimValue), "sanity check"); 1482 reset_heap_region_claim_values(); 1483 } else { 1484 RebuildRSOutOfRegionClosure rebuild_rs(this); 1485 heap_region_iterate(&rebuild_rs); 1486 } 1487 1488 // Rebuild the strong code root lists for each region 1489 rebuild_strong_code_roots(); 1490 1491 if (true) { // FIXME 1492 MetaspaceGC::compute_new_size(); 1493 } 1494 1495 #ifdef TRACESPINNING 1496 ParallelTaskTerminator::print_termination_counts(); 1497 #endif 1498 1499 // Discard all rset updates 1500 JavaThread::dirty_card_queue_set().abandon_logs(); 1501 assert(!G1DeferredRSUpdate 1502 || (G1DeferredRSUpdate && 1503 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1504 1505 _young_list->reset_sampled_info(); 1506 // At this point there should be no regions in the 1507 // entire heap tagged as young. 1508 assert(check_young_list_empty(true /* check_heap */), 1509 "young list should be empty at this point"); 1510 1511 // Update the number of full collections that have been completed. 1512 increment_old_marking_cycles_completed(false /* concurrent */); 1513 1514 _hrs.verify_optional(); 1515 verify_region_sets_optional(); 1516 1517 verify_after_gc(); 1518 1519 // Start a new incremental collection set for the next pause 1520 assert(g1_policy()->collection_set() == NULL, "must be"); 1521 g1_policy()->start_incremental_cset_building(); 1522 1523 // Clear the _cset_fast_test bitmap in anticipation of adding 1524 // regions to the incremental collection set for the next 1525 // evacuation pause. 1526 clear_cset_fast_test(); 1527 1528 init_mutator_alloc_region(); 1529 1530 double end = os::elapsedTime(); 1531 g1_policy()->record_full_collection_end(); 1532 1533 if (G1Log::fine()) { 1534 g1_policy()->print_heap_transition(); 1535 } 1536 1537 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1538 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1539 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1540 // before any GC notifications are raised. 1541 g1mm()->update_sizes(); 1542 1543 gc_epilogue(true); 1544 } 1545 1546 if (G1Log::finer()) { 1547 g1_policy()->print_detailed_heap_transition(true /* full */); 1548 } 1549 1550 print_heap_after_gc(); 1551 trace_heap_after_gc(gc_tracer); 1552 1553 post_full_gc_dump(gc_timer); 1554 1555 gc_timer->register_gc_end(); 1556 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1557 } 1558 1559 return true; 1560 } 1561 1562 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1563 // do_collection() will return whether it succeeded in performing 1564 // the GC. Currently, there is no facility on the 1565 // do_full_collection() API to notify the caller than the collection 1566 // did not succeed (e.g., because it was locked out by the GC 1567 // locker). So, right now, we'll ignore the return value. 1568 bool dummy = do_collection(true, /* explicit_gc */ 1569 clear_all_soft_refs, 1570 0 /* word_size */); 1571 } 1572 1573 // This code is mostly copied from TenuredGeneration. 1574 void 1575 G1CollectedHeap:: 1576 resize_if_necessary_after_full_collection(size_t word_size) { 1577 // Include the current allocation, if any, and bytes that will be 1578 // pre-allocated to support collections, as "used". 1579 const size_t used_after_gc = used(); 1580 const size_t capacity_after_gc = capacity(); 1581 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1582 1583 // This is enforced in arguments.cpp. 1584 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1585 "otherwise the code below doesn't make sense"); 1586 1587 // We don't have floating point command-line arguments 1588 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1589 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1590 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1591 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1592 1593 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1594 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1595 1596 // We have to be careful here as these two calculations can overflow 1597 // 32-bit size_t's. 1598 double used_after_gc_d = (double) used_after_gc; 1599 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1600 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1601 1602 // Let's make sure that they are both under the max heap size, which 1603 // by default will make them fit into a size_t. 1604 double desired_capacity_upper_bound = (double) max_heap_size; 1605 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1606 desired_capacity_upper_bound); 1607 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1608 desired_capacity_upper_bound); 1609 1610 // We can now safely turn them into size_t's. 1611 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1612 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1613 1614 // This assert only makes sense here, before we adjust them 1615 // with respect to the min and max heap size. 1616 assert(minimum_desired_capacity <= maximum_desired_capacity, 1617 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1618 "maximum_desired_capacity = "SIZE_FORMAT, 1619 minimum_desired_capacity, maximum_desired_capacity)); 1620 1621 // Should not be greater than the heap max size. No need to adjust 1622 // it with respect to the heap min size as it's a lower bound (i.e., 1623 // we'll try to make the capacity larger than it, not smaller). 1624 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1625 // Should not be less than the heap min size. No need to adjust it 1626 // with respect to the heap max size as it's an upper bound (i.e., 1627 // we'll try to make the capacity smaller than it, not greater). 1628 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1629 1630 if (capacity_after_gc < minimum_desired_capacity) { 1631 // Don't expand unless it's significant 1632 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1633 ergo_verbose4(ErgoHeapSizing, 1634 "attempt heap expansion", 1635 ergo_format_reason("capacity lower than " 1636 "min desired capacity after Full GC") 1637 ergo_format_byte("capacity") 1638 ergo_format_byte("occupancy") 1639 ergo_format_byte_perc("min desired capacity"), 1640 capacity_after_gc, used_after_gc, 1641 minimum_desired_capacity, (double) MinHeapFreeRatio); 1642 expand(expand_bytes); 1643 1644 // No expansion, now see if we want to shrink 1645 } else if (capacity_after_gc > maximum_desired_capacity) { 1646 // Capacity too large, compute shrinking size 1647 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1648 ergo_verbose4(ErgoHeapSizing, 1649 "attempt heap shrinking", 1650 ergo_format_reason("capacity higher than " 1651 "max desired capacity after Full GC") 1652 ergo_format_byte("capacity") 1653 ergo_format_byte("occupancy") 1654 ergo_format_byte_perc("max desired capacity"), 1655 capacity_after_gc, used_after_gc, 1656 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1657 shrink(shrink_bytes); 1658 } 1659 } 1660 1661 1662 HeapWord* 1663 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1664 bool* succeeded) { 1665 assert_at_safepoint(true /* should_be_vm_thread */); 1666 1667 *succeeded = true; 1668 // Let's attempt the allocation first. 1669 HeapWord* result = 1670 attempt_allocation_at_safepoint(word_size, 1671 false /* expect_null_mutator_alloc_region */); 1672 if (result != NULL) { 1673 assert(*succeeded, "sanity"); 1674 return result; 1675 } 1676 1677 // In a G1 heap, we're supposed to keep allocation from failing by 1678 // incremental pauses. Therefore, at least for now, we'll favor 1679 // expansion over collection. (This might change in the future if we can 1680 // do something smarter than full collection to satisfy a failed alloc.) 1681 result = expand_and_allocate(word_size); 1682 if (result != NULL) { 1683 assert(*succeeded, "sanity"); 1684 return result; 1685 } 1686 1687 // Expansion didn't work, we'll try to do a Full GC. 1688 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1689 false, /* clear_all_soft_refs */ 1690 word_size); 1691 if (!gc_succeeded) { 1692 *succeeded = false; 1693 return NULL; 1694 } 1695 1696 // Retry the allocation 1697 result = attempt_allocation_at_safepoint(word_size, 1698 true /* expect_null_mutator_alloc_region */); 1699 if (result != NULL) { 1700 assert(*succeeded, "sanity"); 1701 return result; 1702 } 1703 1704 // Then, try a Full GC that will collect all soft references. 1705 gc_succeeded = do_collection(false, /* explicit_gc */ 1706 true, /* clear_all_soft_refs */ 1707 word_size); 1708 if (!gc_succeeded) { 1709 *succeeded = false; 1710 return NULL; 1711 } 1712 1713 // Retry the allocation once more 1714 result = attempt_allocation_at_safepoint(word_size, 1715 true /* expect_null_mutator_alloc_region */); 1716 if (result != NULL) { 1717 assert(*succeeded, "sanity"); 1718 return result; 1719 } 1720 1721 assert(!collector_policy()->should_clear_all_soft_refs(), 1722 "Flag should have been handled and cleared prior to this point"); 1723 1724 // What else? We might try synchronous finalization later. If the total 1725 // space available is large enough for the allocation, then a more 1726 // complete compaction phase than we've tried so far might be 1727 // appropriate. 1728 assert(*succeeded, "sanity"); 1729 return NULL; 1730 } 1731 1732 // Attempting to expand the heap sufficiently 1733 // to support an allocation of the given "word_size". If 1734 // successful, perform the allocation and return the address of the 1735 // allocated block, or else "NULL". 1736 1737 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1738 assert_at_safepoint(true /* should_be_vm_thread */); 1739 1740 verify_region_sets_optional(); 1741 1742 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1743 ergo_verbose1(ErgoHeapSizing, 1744 "attempt heap expansion", 1745 ergo_format_reason("allocation request failed") 1746 ergo_format_byte("allocation request"), 1747 word_size * HeapWordSize); 1748 if (expand(expand_bytes)) { 1749 _hrs.verify_optional(); 1750 verify_region_sets_optional(); 1751 return attempt_allocation_at_safepoint(word_size, 1752 false /* expect_null_mutator_alloc_region */); 1753 } 1754 return NULL; 1755 } 1756 1757 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1758 HeapWord* new_end) { 1759 assert(old_end != new_end, "don't call this otherwise"); 1760 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1761 1762 // Update the committed mem region. 1763 _g1_committed.set_end(new_end); 1764 // Tell the card table about the update. 1765 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1766 // Tell the BOT about the update. 1767 _bot_shared->resize(_g1_committed.word_size()); 1768 // Tell the hot card cache about the update 1769 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1770 } 1771 1772 bool G1CollectedHeap::expand(size_t expand_bytes) { 1773 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1774 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1775 HeapRegion::GrainBytes); 1776 ergo_verbose2(ErgoHeapSizing, 1777 "expand the heap", 1778 ergo_format_byte("requested expansion amount") 1779 ergo_format_byte("attempted expansion amount"), 1780 expand_bytes, aligned_expand_bytes); 1781 1782 if (_g1_storage.uncommitted_size() == 0) { 1783 ergo_verbose0(ErgoHeapSizing, 1784 "did not expand the heap", 1785 ergo_format_reason("heap already fully expanded")); 1786 return false; 1787 } 1788 1789 // First commit the memory. 1790 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1791 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1792 if (successful) { 1793 // Then propagate this update to the necessary data structures. 1794 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1795 update_committed_space(old_end, new_end); 1796 1797 FreeRegionList expansion_list("Local Expansion List", NULL); 1798 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1799 assert(mr.start() == old_end, "post-condition"); 1800 // mr might be a smaller region than what was requested if 1801 // expand_by() was unable to allocate the HeapRegion instances 1802 assert(mr.end() <= new_end, "post-condition"); 1803 1804 size_t actual_expand_bytes = mr.byte_size(); 1805 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1806 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1807 "post-condition"); 1808 if (actual_expand_bytes < aligned_expand_bytes) { 1809 // We could not expand _hrs to the desired size. In this case we 1810 // need to shrink the committed space accordingly. 1811 assert(mr.end() < new_end, "invariant"); 1812 1813 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1814 // First uncommit the memory. 1815 _g1_storage.shrink_by(diff_bytes); 1816 // Then propagate this update to the necessary data structures. 1817 update_committed_space(new_end, mr.end()); 1818 } 1819 _free_list.add_as_tail(&expansion_list); 1820 1821 if (_hr_printer.is_active()) { 1822 HeapWord* curr = mr.start(); 1823 while (curr < mr.end()) { 1824 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1825 _hr_printer.commit(curr, curr_end); 1826 curr = curr_end; 1827 } 1828 assert(curr == mr.end(), "post-condition"); 1829 } 1830 g1_policy()->record_new_heap_size(n_regions()); 1831 } else { 1832 ergo_verbose0(ErgoHeapSizing, 1833 "did not expand the heap", 1834 ergo_format_reason("heap expansion operation failed")); 1835 // The expansion of the virtual storage space was unsuccessful. 1836 // Let's see if it was because we ran out of swap. 1837 if (G1ExitOnExpansionFailure && 1838 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1839 // We had head room... 1840 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1841 } 1842 } 1843 return successful; 1844 } 1845 1846 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1847 size_t aligned_shrink_bytes = 1848 ReservedSpace::page_align_size_down(shrink_bytes); 1849 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1850 HeapRegion::GrainBytes); 1851 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1852 1853 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1854 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1855 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1856 1857 ergo_verbose3(ErgoHeapSizing, 1858 "shrink the heap", 1859 ergo_format_byte("requested shrinking amount") 1860 ergo_format_byte("aligned shrinking amount") 1861 ergo_format_byte("attempted shrinking amount"), 1862 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1863 if (num_regions_removed > 0) { 1864 _g1_storage.shrink_by(shrunk_bytes); 1865 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1866 1867 if (_hr_printer.is_active()) { 1868 HeapWord* curr = old_end; 1869 while (curr > new_end) { 1870 HeapWord* curr_end = curr; 1871 curr -= HeapRegion::GrainWords; 1872 _hr_printer.uncommit(curr, curr_end); 1873 } 1874 } 1875 1876 _expansion_regions += num_regions_removed; 1877 update_committed_space(old_end, new_end); 1878 HeapRegionRemSet::shrink_heap(n_regions()); 1879 g1_policy()->record_new_heap_size(n_regions()); 1880 } else { 1881 ergo_verbose0(ErgoHeapSizing, 1882 "did not shrink the heap", 1883 ergo_format_reason("heap shrinking operation failed")); 1884 } 1885 } 1886 1887 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1888 verify_region_sets_optional(); 1889 1890 // We should only reach here at the end of a Full GC which means we 1891 // should not not be holding to any GC alloc regions. The method 1892 // below will make sure of that and do any remaining clean up. 1893 abandon_gc_alloc_regions(); 1894 1895 // Instead of tearing down / rebuilding the free lists here, we 1896 // could instead use the remove_all_pending() method on free_list to 1897 // remove only the ones that we need to remove. 1898 tear_down_region_sets(true /* free_list_only */); 1899 shrink_helper(shrink_bytes); 1900 rebuild_region_sets(true /* free_list_only */); 1901 1902 _hrs.verify_optional(); 1903 verify_region_sets_optional(); 1904 } 1905 1906 // Public methods. 1907 1908 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1909 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1910 #endif // _MSC_VER 1911 1912 1913 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1914 SharedHeap(policy_), 1915 _g1_policy(policy_), 1916 _dirty_card_queue_set(false), 1917 _into_cset_dirty_card_queue_set(false), 1918 _is_alive_closure_cm(this), 1919 _is_alive_closure_stw(this), 1920 _ref_processor_cm(NULL), 1921 _ref_processor_stw(NULL), 1922 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1923 _bot_shared(NULL), 1924 _evac_failure_scan_stack(NULL), 1925 _mark_in_progress(false), 1926 _cg1r(NULL), _summary_bytes_used(0), 1927 _g1mm(NULL), 1928 _refine_cte_cl(NULL), 1929 _full_collection(false), 1930 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()), 1931 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1932 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1933 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1934 _free_regions_coming(false), 1935 _young_list(new YoungList(this)), 1936 _gc_time_stamp(0), 1937 _retained_old_gc_alloc_region(NULL), 1938 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1939 _old_plab_stats(OldPLABSize, PLABWeight), 1940 _expand_heap_after_alloc_failure(true), 1941 _surviving_young_words(NULL), 1942 _old_marking_cycles_started(0), 1943 _old_marking_cycles_completed(0), 1944 _concurrent_cycle_started(false), 1945 _in_cset_fast_test(NULL), 1946 _in_cset_fast_test_base(NULL), 1947 _dirty_cards_region_list(NULL), 1948 _worker_cset_start_region(NULL), 1949 _worker_cset_start_region_time_stamp(NULL), 1950 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1951 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1952 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1953 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1954 1955 _g1h = this; 1956 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1957 vm_exit_during_initialization("Failed necessary allocation."); 1958 } 1959 1960 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1961 1962 int n_queues = MAX2((int)ParallelGCThreads, 1); 1963 _task_queues = new RefToScanQueueSet(n_queues); 1964 1965 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1966 assert(n_rem_sets > 0, "Invariant."); 1967 1968 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1969 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1970 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1971 1972 for (int i = 0; i < n_queues; i++) { 1973 RefToScanQueue* q = new RefToScanQueue(); 1974 q->initialize(); 1975 _task_queues->register_queue(i, q); 1976 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1977 } 1978 clear_cset_start_regions(); 1979 1980 // Initialize the G1EvacuationFailureALot counters and flags. 1981 NOT_PRODUCT(reset_evacuation_should_fail();) 1982 1983 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1984 } 1985 1986 jint G1CollectedHeap::initialize() { 1987 CollectedHeap::pre_initialize(); 1988 os::enable_vtime(); 1989 1990 G1Log::init(); 1991 1992 // Necessary to satisfy locking discipline assertions. 1993 1994 MutexLocker x(Heap_lock); 1995 1996 // We have to initialize the printer before committing the heap, as 1997 // it will be used then. 1998 _hr_printer.set_active(G1PrintHeapRegions); 1999 2000 // While there are no constraints in the GC code that HeapWordSize 2001 // be any particular value, there are multiple other areas in the 2002 // system which believe this to be true (e.g. oop->object_size in some 2003 // cases incorrectly returns the size in wordSize units rather than 2004 // HeapWordSize). 2005 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2006 2007 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2008 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2009 size_t heap_alignment = collector_policy()->heap_alignment(); 2010 2011 // Ensure that the sizes are properly aligned. 2012 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2013 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2014 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2015 2016 _cg1r = new ConcurrentG1Refine(this); 2017 2018 // Reserve the maximum. 2019 2020 // When compressed oops are enabled, the preferred heap base 2021 // is calculated by subtracting the requested size from the 2022 // 32Gb boundary and using the result as the base address for 2023 // heap reservation. If the requested size is not aligned to 2024 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2025 // into the ReservedHeapSpace constructor) then the actual 2026 // base of the reserved heap may end up differing from the 2027 // address that was requested (i.e. the preferred heap base). 2028 // If this happens then we could end up using a non-optimal 2029 // compressed oops mode. 2030 2031 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2032 heap_alignment); 2033 2034 // It is important to do this in a way such that concurrent readers can't 2035 // temporarily think something is in the heap. (I've actually seen this 2036 // happen in asserts: DLD.) 2037 _reserved.set_word_size(0); 2038 _reserved.set_start((HeapWord*)heap_rs.base()); 2039 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2040 2041 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2042 2043 // Create the gen rem set (and barrier set) for the entire reserved region. 2044 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2045 set_barrier_set(rem_set()->bs()); 2046 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2047 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2048 return JNI_ENOMEM; 2049 } 2050 2051 // Also create a G1 rem set. 2052 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2053 2054 // Carve out the G1 part of the heap. 2055 2056 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2057 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2058 g1_rs.size()/HeapWordSize); 2059 2060 _g1_storage.initialize(g1_rs, 0); 2061 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2062 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2063 (HeapWord*) _g1_reserved.end()); 2064 assert(_hrs.max_length() == _expansion_regions, 2065 err_msg("max length: %u expansion regions: %u", 2066 _hrs.max_length(), _expansion_regions)); 2067 2068 // Do later initialization work for concurrent refinement. 2069 _cg1r->init(); 2070 2071 // 6843694 - ensure that the maximum region index can fit 2072 // in the remembered set structures. 2073 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2074 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2075 2076 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2077 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2078 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2079 "too many cards per region"); 2080 2081 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2082 2083 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2084 heap_word_size(init_byte_size)); 2085 2086 _g1h = this; 2087 2088 _in_cset_fast_test_length = max_regions(); 2089 _in_cset_fast_test_base = 2090 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC); 2091 2092 // We're biasing _in_cset_fast_test to avoid subtracting the 2093 // beginning of the heap every time we want to index; basically 2094 // it's the same with what we do with the card table. 2095 _in_cset_fast_test = _in_cset_fast_test_base - 2096 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes); 2097 2098 // Clear the _cset_fast_test bitmap in anticipation of adding 2099 // regions to the incremental collection set for the first 2100 // evacuation pause. 2101 clear_cset_fast_test(); 2102 2103 // Create the ConcurrentMark data structure and thread. 2104 // (Must do this late, so that "max_regions" is defined.) 2105 _cm = new ConcurrentMark(this, heap_rs); 2106 if (_cm == NULL || !_cm->completed_initialization()) { 2107 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2108 return JNI_ENOMEM; 2109 } 2110 _cmThread = _cm->cmThread(); 2111 2112 // Initialize the from_card cache structure of HeapRegionRemSet. 2113 HeapRegionRemSet::init_heap(max_regions()); 2114 2115 // Now expand into the initial heap size. 2116 if (!expand(init_byte_size)) { 2117 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2118 return JNI_ENOMEM; 2119 } 2120 2121 // Perform any initialization actions delegated to the policy. 2122 g1_policy()->init(); 2123 2124 _refine_cte_cl = 2125 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(), 2126 g1_rem_set(), 2127 concurrent_g1_refine()); 2128 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 2129 2130 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2131 SATB_Q_FL_lock, 2132 G1SATBProcessCompletedThreshold, 2133 Shared_SATB_Q_lock); 2134 2135 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2136 DirtyCardQ_FL_lock, 2137 concurrent_g1_refine()->yellow_zone(), 2138 concurrent_g1_refine()->red_zone(), 2139 Shared_DirtyCardQ_lock); 2140 2141 if (G1DeferredRSUpdate) { 2142 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2143 DirtyCardQ_FL_lock, 2144 -1, // never trigger processing 2145 -1, // no limit on length 2146 Shared_DirtyCardQ_lock, 2147 &JavaThread::dirty_card_queue_set()); 2148 } 2149 2150 // Initialize the card queue set used to hold cards containing 2151 // references into the collection set. 2152 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, 2153 DirtyCardQ_FL_lock, 2154 -1, // never trigger processing 2155 -1, // no limit on length 2156 Shared_DirtyCardQ_lock, 2157 &JavaThread::dirty_card_queue_set()); 2158 2159 // In case we're keeping closure specialization stats, initialize those 2160 // counts and that mechanism. 2161 SpecializationStats::clear(); 2162 2163 // Here we allocate the dummy full region that is required by the 2164 // G1AllocRegion class. If we don't pass an address in the reserved 2165 // space here, lots of asserts fire. 2166 2167 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2168 _g1_reserved.start()); 2169 // We'll re-use the same region whether the alloc region will 2170 // require BOT updates or not and, if it doesn't, then a non-young 2171 // region will complain that it cannot support allocations without 2172 // BOT updates. So we'll tag the dummy region as young to avoid that. 2173 dummy_region->set_young(); 2174 // Make sure it's full. 2175 dummy_region->set_top(dummy_region->end()); 2176 G1AllocRegion::setup(this, dummy_region); 2177 2178 init_mutator_alloc_region(); 2179 2180 // Do create of the monitoring and management support so that 2181 // values in the heap have been properly initialized. 2182 _g1mm = new G1MonitoringSupport(this); 2183 2184 return JNI_OK; 2185 } 2186 2187 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2188 return HeapRegion::max_region_size(); 2189 } 2190 2191 void G1CollectedHeap::ref_processing_init() { 2192 // Reference processing in G1 currently works as follows: 2193 // 2194 // * There are two reference processor instances. One is 2195 // used to record and process discovered references 2196 // during concurrent marking; the other is used to 2197 // record and process references during STW pauses 2198 // (both full and incremental). 2199 // * Both ref processors need to 'span' the entire heap as 2200 // the regions in the collection set may be dotted around. 2201 // 2202 // * For the concurrent marking ref processor: 2203 // * Reference discovery is enabled at initial marking. 2204 // * Reference discovery is disabled and the discovered 2205 // references processed etc during remarking. 2206 // * Reference discovery is MT (see below). 2207 // * Reference discovery requires a barrier (see below). 2208 // * Reference processing may or may not be MT 2209 // (depending on the value of ParallelRefProcEnabled 2210 // and ParallelGCThreads). 2211 // * A full GC disables reference discovery by the CM 2212 // ref processor and abandons any entries on it's 2213 // discovered lists. 2214 // 2215 // * For the STW processor: 2216 // * Non MT discovery is enabled at the start of a full GC. 2217 // * Processing and enqueueing during a full GC is non-MT. 2218 // * During a full GC, references are processed after marking. 2219 // 2220 // * Discovery (may or may not be MT) is enabled at the start 2221 // of an incremental evacuation pause. 2222 // * References are processed near the end of a STW evacuation pause. 2223 // * For both types of GC: 2224 // * Discovery is atomic - i.e. not concurrent. 2225 // * Reference discovery will not need a barrier. 2226 2227 SharedHeap::ref_processing_init(); 2228 MemRegion mr = reserved_region(); 2229 2230 // Concurrent Mark ref processor 2231 _ref_processor_cm = 2232 new ReferenceProcessor(mr, // span 2233 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2234 // mt processing 2235 (int) ParallelGCThreads, 2236 // degree of mt processing 2237 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2238 // mt discovery 2239 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2240 // degree of mt discovery 2241 false, 2242 // Reference discovery is not atomic 2243 &_is_alive_closure_cm, 2244 // is alive closure 2245 // (for efficiency/performance) 2246 true); 2247 // Setting next fields of discovered 2248 // lists requires a barrier. 2249 2250 // STW ref processor 2251 _ref_processor_stw = 2252 new ReferenceProcessor(mr, // span 2253 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2254 // mt processing 2255 MAX2((int)ParallelGCThreads, 1), 2256 // degree of mt processing 2257 (ParallelGCThreads > 1), 2258 // mt discovery 2259 MAX2((int)ParallelGCThreads, 1), 2260 // degree of mt discovery 2261 true, 2262 // Reference discovery is atomic 2263 &_is_alive_closure_stw, 2264 // is alive closure 2265 // (for efficiency/performance) 2266 false); 2267 // Setting next fields of discovered 2268 // lists does not require a barrier. 2269 } 2270 2271 size_t G1CollectedHeap::capacity() const { 2272 return _g1_committed.byte_size(); 2273 } 2274 2275 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2276 assert(!hr->continuesHumongous(), "pre-condition"); 2277 hr->reset_gc_time_stamp(); 2278 if (hr->startsHumongous()) { 2279 uint first_index = hr->hrs_index() + 1; 2280 uint last_index = hr->last_hc_index(); 2281 for (uint i = first_index; i < last_index; i += 1) { 2282 HeapRegion* chr = region_at(i); 2283 assert(chr->continuesHumongous(), "sanity"); 2284 chr->reset_gc_time_stamp(); 2285 } 2286 } 2287 } 2288 2289 #ifndef PRODUCT 2290 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2291 private: 2292 unsigned _gc_time_stamp; 2293 bool _failures; 2294 2295 public: 2296 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2297 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2298 2299 virtual bool doHeapRegion(HeapRegion* hr) { 2300 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2301 if (_gc_time_stamp != region_gc_time_stamp) { 2302 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2303 "expected %d", HR_FORMAT_PARAMS(hr), 2304 region_gc_time_stamp, _gc_time_stamp); 2305 _failures = true; 2306 } 2307 return false; 2308 } 2309 2310 bool failures() { return _failures; } 2311 }; 2312 2313 void G1CollectedHeap::check_gc_time_stamps() { 2314 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2315 heap_region_iterate(&cl); 2316 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2317 } 2318 #endif // PRODUCT 2319 2320 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2321 DirtyCardQueue* into_cset_dcq, 2322 bool concurrent, 2323 int worker_i) { 2324 // Clean cards in the hot card cache 2325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2326 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2327 2328 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2329 int n_completed_buffers = 0; 2330 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2331 n_completed_buffers++; 2332 } 2333 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2334 dcqs.clear_n_completed_buffers(); 2335 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2336 } 2337 2338 2339 // Computes the sum of the storage used by the various regions. 2340 2341 size_t G1CollectedHeap::used() const { 2342 assert(Heap_lock->owner() != NULL, 2343 "Should be owned on this thread's behalf."); 2344 size_t result = _summary_bytes_used; 2345 // Read only once in case it is set to NULL concurrently 2346 HeapRegion* hr = _mutator_alloc_region.get(); 2347 if (hr != NULL) 2348 result += hr->used(); 2349 return result; 2350 } 2351 2352 size_t G1CollectedHeap::used_unlocked() const { 2353 size_t result = _summary_bytes_used; 2354 return result; 2355 } 2356 2357 class SumUsedClosure: public HeapRegionClosure { 2358 size_t _used; 2359 public: 2360 SumUsedClosure() : _used(0) {} 2361 bool doHeapRegion(HeapRegion* r) { 2362 if (!r->continuesHumongous()) { 2363 _used += r->used(); 2364 } 2365 return false; 2366 } 2367 size_t result() { return _used; } 2368 }; 2369 2370 size_t G1CollectedHeap::recalculate_used() const { 2371 SumUsedClosure blk; 2372 heap_region_iterate(&blk); 2373 return blk.result(); 2374 } 2375 2376 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2377 switch (cause) { 2378 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2379 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2380 case GCCause::_g1_humongous_allocation: return true; 2381 default: return false; 2382 } 2383 } 2384 2385 #ifndef PRODUCT 2386 void G1CollectedHeap::allocate_dummy_regions() { 2387 // Let's fill up most of the region 2388 size_t word_size = HeapRegion::GrainWords - 1024; 2389 // And as a result the region we'll allocate will be humongous. 2390 guarantee(isHumongous(word_size), "sanity"); 2391 2392 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2393 // Let's use the existing mechanism for the allocation 2394 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2395 if (dummy_obj != NULL) { 2396 MemRegion mr(dummy_obj, word_size); 2397 CollectedHeap::fill_with_object(mr); 2398 } else { 2399 // If we can't allocate once, we probably cannot allocate 2400 // again. Let's get out of the loop. 2401 break; 2402 } 2403 } 2404 } 2405 #endif // !PRODUCT 2406 2407 void G1CollectedHeap::increment_old_marking_cycles_started() { 2408 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2409 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2410 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2411 _old_marking_cycles_started, _old_marking_cycles_completed)); 2412 2413 _old_marking_cycles_started++; 2414 } 2415 2416 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2417 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2418 2419 // We assume that if concurrent == true, then the caller is a 2420 // concurrent thread that was joined the Suspendible Thread 2421 // Set. If there's ever a cheap way to check this, we should add an 2422 // assert here. 2423 2424 // Given that this method is called at the end of a Full GC or of a 2425 // concurrent cycle, and those can be nested (i.e., a Full GC can 2426 // interrupt a concurrent cycle), the number of full collections 2427 // completed should be either one (in the case where there was no 2428 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2429 // behind the number of full collections started. 2430 2431 // This is the case for the inner caller, i.e. a Full GC. 2432 assert(concurrent || 2433 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2434 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2435 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2436 "is inconsistent with _old_marking_cycles_completed = %u", 2437 _old_marking_cycles_started, _old_marking_cycles_completed)); 2438 2439 // This is the case for the outer caller, i.e. the concurrent cycle. 2440 assert(!concurrent || 2441 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2442 err_msg("for outer caller (concurrent cycle): " 2443 "_old_marking_cycles_started = %u " 2444 "is inconsistent with _old_marking_cycles_completed = %u", 2445 _old_marking_cycles_started, _old_marking_cycles_completed)); 2446 2447 _old_marking_cycles_completed += 1; 2448 2449 // We need to clear the "in_progress" flag in the CM thread before 2450 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2451 // is set) so that if a waiter requests another System.gc() it doesn't 2452 // incorrectly see that a marking cycle is still in progress. 2453 if (concurrent) { 2454 _cmThread->clear_in_progress(); 2455 } 2456 2457 // This notify_all() will ensure that a thread that called 2458 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2459 // and it's waiting for a full GC to finish will be woken up. It is 2460 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2461 FullGCCount_lock->notify_all(); 2462 } 2463 2464 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2465 _concurrent_cycle_started = true; 2466 _gc_timer_cm->register_gc_start(start_time); 2467 2468 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2469 trace_heap_before_gc(_gc_tracer_cm); 2470 } 2471 2472 void G1CollectedHeap::register_concurrent_cycle_end() { 2473 if (_concurrent_cycle_started) { 2474 if (_cm->has_aborted()) { 2475 _gc_tracer_cm->report_concurrent_mode_failure(); 2476 } 2477 2478 _gc_timer_cm->register_gc_end(); 2479 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2480 2481 _concurrent_cycle_started = false; 2482 } 2483 } 2484 2485 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2486 if (_concurrent_cycle_started) { 2487 trace_heap_after_gc(_gc_tracer_cm); 2488 } 2489 } 2490 2491 G1YCType G1CollectedHeap::yc_type() { 2492 bool is_young = g1_policy()->gcs_are_young(); 2493 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2494 bool is_during_mark = mark_in_progress(); 2495 2496 if (is_initial_mark) { 2497 return InitialMark; 2498 } else if (is_during_mark) { 2499 return DuringMark; 2500 } else if (is_young) { 2501 return Normal; 2502 } else { 2503 return Mixed; 2504 } 2505 } 2506 2507 void G1CollectedHeap::collect(GCCause::Cause cause) { 2508 assert_heap_not_locked(); 2509 2510 unsigned int gc_count_before; 2511 unsigned int old_marking_count_before; 2512 bool retry_gc; 2513 2514 do { 2515 retry_gc = false; 2516 2517 { 2518 MutexLocker ml(Heap_lock); 2519 2520 // Read the GC count while holding the Heap_lock 2521 gc_count_before = total_collections(); 2522 old_marking_count_before = _old_marking_cycles_started; 2523 } 2524 2525 if (should_do_concurrent_full_gc(cause)) { 2526 // Schedule an initial-mark evacuation pause that will start a 2527 // concurrent cycle. We're setting word_size to 0 which means that 2528 // we are not requesting a post-GC allocation. 2529 VM_G1IncCollectionPause op(gc_count_before, 2530 0, /* word_size */ 2531 true, /* should_initiate_conc_mark */ 2532 g1_policy()->max_pause_time_ms(), 2533 cause); 2534 2535 VMThread::execute(&op); 2536 if (!op.pause_succeeded()) { 2537 if (old_marking_count_before == _old_marking_cycles_started) { 2538 retry_gc = op.should_retry_gc(); 2539 } else { 2540 // A Full GC happened while we were trying to schedule the 2541 // initial-mark GC. No point in starting a new cycle given 2542 // that the whole heap was collected anyway. 2543 } 2544 2545 if (retry_gc) { 2546 if (GC_locker::is_active_and_needs_gc()) { 2547 GC_locker::stall_until_clear(); 2548 } 2549 } 2550 } 2551 } else { 2552 if (cause == GCCause::_gc_locker 2553 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2554 2555 // Schedule a standard evacuation pause. We're setting word_size 2556 // to 0 which means that we are not requesting a post-GC allocation. 2557 VM_G1IncCollectionPause op(gc_count_before, 2558 0, /* word_size */ 2559 false, /* should_initiate_conc_mark */ 2560 g1_policy()->max_pause_time_ms(), 2561 cause); 2562 VMThread::execute(&op); 2563 } else { 2564 // Schedule a Full GC. 2565 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2566 VMThread::execute(&op); 2567 } 2568 } 2569 } while (retry_gc); 2570 } 2571 2572 bool G1CollectedHeap::is_in(const void* p) const { 2573 if (_g1_committed.contains(p)) { 2574 // Given that we know that p is in the committed space, 2575 // heap_region_containing_raw() should successfully 2576 // return the containing region. 2577 HeapRegion* hr = heap_region_containing_raw(p); 2578 return hr->is_in(p); 2579 } else { 2580 return false; 2581 } 2582 } 2583 2584 // Iteration functions. 2585 2586 // Iterates an OopClosure over all ref-containing fields of objects 2587 // within a HeapRegion. 2588 2589 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2590 MemRegion _mr; 2591 ExtendedOopClosure* _cl; 2592 public: 2593 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2594 : _mr(mr), _cl(cl) {} 2595 bool doHeapRegion(HeapRegion* r) { 2596 if (!r->continuesHumongous()) { 2597 r->oop_iterate(_cl); 2598 } 2599 return false; 2600 } 2601 }; 2602 2603 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2604 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2605 heap_region_iterate(&blk); 2606 } 2607 2608 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2609 IterateOopClosureRegionClosure blk(mr, cl); 2610 heap_region_iterate(&blk); 2611 } 2612 2613 // Iterates an ObjectClosure over all objects within a HeapRegion. 2614 2615 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2616 ObjectClosure* _cl; 2617 public: 2618 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2619 bool doHeapRegion(HeapRegion* r) { 2620 if (! r->continuesHumongous()) { 2621 r->object_iterate(_cl); 2622 } 2623 return false; 2624 } 2625 }; 2626 2627 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2628 IterateObjectClosureRegionClosure blk(cl); 2629 heap_region_iterate(&blk); 2630 } 2631 2632 // Calls a SpaceClosure on a HeapRegion. 2633 2634 class SpaceClosureRegionClosure: public HeapRegionClosure { 2635 SpaceClosure* _cl; 2636 public: 2637 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2638 bool doHeapRegion(HeapRegion* r) { 2639 _cl->do_space(r); 2640 return false; 2641 } 2642 }; 2643 2644 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2645 SpaceClosureRegionClosure blk(cl); 2646 heap_region_iterate(&blk); 2647 } 2648 2649 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2650 _hrs.iterate(cl); 2651 } 2652 2653 void 2654 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2655 uint worker_id, 2656 uint no_of_par_workers, 2657 jint claim_value) { 2658 const uint regions = n_regions(); 2659 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2660 no_of_par_workers : 2661 1); 2662 assert(UseDynamicNumberOfGCThreads || 2663 no_of_par_workers == workers()->total_workers(), 2664 "Non dynamic should use fixed number of workers"); 2665 // try to spread out the starting points of the workers 2666 const HeapRegion* start_hr = 2667 start_region_for_worker(worker_id, no_of_par_workers); 2668 const uint start_index = start_hr->hrs_index(); 2669 2670 // each worker will actually look at all regions 2671 for (uint count = 0; count < regions; ++count) { 2672 const uint index = (start_index + count) % regions; 2673 assert(0 <= index && index < regions, "sanity"); 2674 HeapRegion* r = region_at(index); 2675 // we'll ignore "continues humongous" regions (we'll process them 2676 // when we come across their corresponding "start humongous" 2677 // region) and regions already claimed 2678 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2679 continue; 2680 } 2681 // OK, try to claim it 2682 if (r->claimHeapRegion(claim_value)) { 2683 // success! 2684 assert(!r->continuesHumongous(), "sanity"); 2685 if (r->startsHumongous()) { 2686 // If the region is "starts humongous" we'll iterate over its 2687 // "continues humongous" first; in fact we'll do them 2688 // first. The order is important. In on case, calling the 2689 // closure on the "starts humongous" region might de-allocate 2690 // and clear all its "continues humongous" regions and, as a 2691 // result, we might end up processing them twice. So, we'll do 2692 // them first (notice: most closures will ignore them anyway) and 2693 // then we'll do the "starts humongous" region. 2694 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2695 HeapRegion* chr = region_at(ch_index); 2696 2697 // if the region has already been claimed or it's not 2698 // "continues humongous" we're done 2699 if (chr->claim_value() == claim_value || 2700 !chr->continuesHumongous()) { 2701 break; 2702 } 2703 2704 // No one should have claimed it directly. We can given 2705 // that we claimed its "starts humongous" region. 2706 assert(chr->claim_value() != claim_value, "sanity"); 2707 assert(chr->humongous_start_region() == r, "sanity"); 2708 2709 if (chr->claimHeapRegion(claim_value)) { 2710 // we should always be able to claim it; no one else should 2711 // be trying to claim this region 2712 2713 bool res2 = cl->doHeapRegion(chr); 2714 assert(!res2, "Should not abort"); 2715 2716 // Right now, this holds (i.e., no closure that actually 2717 // does something with "continues humongous" regions 2718 // clears them). We might have to weaken it in the future, 2719 // but let's leave these two asserts here for extra safety. 2720 assert(chr->continuesHumongous(), "should still be the case"); 2721 assert(chr->humongous_start_region() == r, "sanity"); 2722 } else { 2723 guarantee(false, "we should not reach here"); 2724 } 2725 } 2726 } 2727 2728 assert(!r->continuesHumongous(), "sanity"); 2729 bool res = cl->doHeapRegion(r); 2730 assert(!res, "Should not abort"); 2731 } 2732 } 2733 } 2734 2735 class ResetClaimValuesClosure: public HeapRegionClosure { 2736 public: 2737 bool doHeapRegion(HeapRegion* r) { 2738 r->set_claim_value(HeapRegion::InitialClaimValue); 2739 return false; 2740 } 2741 }; 2742 2743 void G1CollectedHeap::reset_heap_region_claim_values() { 2744 ResetClaimValuesClosure blk; 2745 heap_region_iterate(&blk); 2746 } 2747 2748 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2749 ResetClaimValuesClosure blk; 2750 collection_set_iterate(&blk); 2751 } 2752 2753 #ifdef ASSERT 2754 // This checks whether all regions in the heap have the correct claim 2755 // value. I also piggy-backed on this a check to ensure that the 2756 // humongous_start_region() information on "continues humongous" 2757 // regions is correct. 2758 2759 class CheckClaimValuesClosure : public HeapRegionClosure { 2760 private: 2761 jint _claim_value; 2762 uint _failures; 2763 HeapRegion* _sh_region; 2764 2765 public: 2766 CheckClaimValuesClosure(jint claim_value) : 2767 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2768 bool doHeapRegion(HeapRegion* r) { 2769 if (r->claim_value() != _claim_value) { 2770 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2771 "claim value = %d, should be %d", 2772 HR_FORMAT_PARAMS(r), 2773 r->claim_value(), _claim_value); 2774 ++_failures; 2775 } 2776 if (!r->isHumongous()) { 2777 _sh_region = NULL; 2778 } else if (r->startsHumongous()) { 2779 _sh_region = r; 2780 } else if (r->continuesHumongous()) { 2781 if (r->humongous_start_region() != _sh_region) { 2782 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2783 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2784 HR_FORMAT_PARAMS(r), 2785 r->humongous_start_region(), 2786 _sh_region); 2787 ++_failures; 2788 } 2789 } 2790 return false; 2791 } 2792 uint failures() { return _failures; } 2793 }; 2794 2795 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2796 CheckClaimValuesClosure cl(claim_value); 2797 heap_region_iterate(&cl); 2798 return cl.failures() == 0; 2799 } 2800 2801 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2802 private: 2803 jint _claim_value; 2804 uint _failures; 2805 2806 public: 2807 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2808 _claim_value(claim_value), _failures(0) { } 2809 2810 uint failures() { return _failures; } 2811 2812 bool doHeapRegion(HeapRegion* hr) { 2813 assert(hr->in_collection_set(), "how?"); 2814 assert(!hr->isHumongous(), "H-region in CSet"); 2815 if (hr->claim_value() != _claim_value) { 2816 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2817 "claim value = %d, should be %d", 2818 HR_FORMAT_PARAMS(hr), 2819 hr->claim_value(), _claim_value); 2820 _failures += 1; 2821 } 2822 return false; 2823 } 2824 }; 2825 2826 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2827 CheckClaimValuesInCSetHRClosure cl(claim_value); 2828 collection_set_iterate(&cl); 2829 return cl.failures() == 0; 2830 } 2831 #endif // ASSERT 2832 2833 // Clear the cached CSet starting regions and (more importantly) 2834 // the time stamps. Called when we reset the GC time stamp. 2835 void G1CollectedHeap::clear_cset_start_regions() { 2836 assert(_worker_cset_start_region != NULL, "sanity"); 2837 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2838 2839 int n_queues = MAX2((int)ParallelGCThreads, 1); 2840 for (int i = 0; i < n_queues; i++) { 2841 _worker_cset_start_region[i] = NULL; 2842 _worker_cset_start_region_time_stamp[i] = 0; 2843 } 2844 } 2845 2846 // Given the id of a worker, obtain or calculate a suitable 2847 // starting region for iterating over the current collection set. 2848 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) { 2849 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2850 2851 HeapRegion* result = NULL; 2852 unsigned gc_time_stamp = get_gc_time_stamp(); 2853 2854 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2855 // Cached starting region for current worker was set 2856 // during the current pause - so it's valid. 2857 // Note: the cached starting heap region may be NULL 2858 // (when the collection set is empty). 2859 result = _worker_cset_start_region[worker_i]; 2860 assert(result == NULL || result->in_collection_set(), "sanity"); 2861 return result; 2862 } 2863 2864 // The cached entry was not valid so let's calculate 2865 // a suitable starting heap region for this worker. 2866 2867 // We want the parallel threads to start their collection 2868 // set iteration at different collection set regions to 2869 // avoid contention. 2870 // If we have: 2871 // n collection set regions 2872 // p threads 2873 // Then thread t will start at region floor ((t * n) / p) 2874 2875 result = g1_policy()->collection_set(); 2876 if (G1CollectedHeap::use_parallel_gc_threads()) { 2877 uint cs_size = g1_policy()->cset_region_length(); 2878 uint active_workers = workers()->active_workers(); 2879 assert(UseDynamicNumberOfGCThreads || 2880 active_workers == workers()->total_workers(), 2881 "Unless dynamic should use total workers"); 2882 2883 uint end_ind = (cs_size * worker_i) / active_workers; 2884 uint start_ind = 0; 2885 2886 if (worker_i > 0 && 2887 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2888 // Previous workers starting region is valid 2889 // so let's iterate from there 2890 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2891 result = _worker_cset_start_region[worker_i - 1]; 2892 } 2893 2894 for (uint i = start_ind; i < end_ind; i++) { 2895 result = result->next_in_collection_set(); 2896 } 2897 } 2898 2899 // Note: the calculated starting heap region may be NULL 2900 // (when the collection set is empty). 2901 assert(result == NULL || result->in_collection_set(), "sanity"); 2902 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2903 "should be updated only once per pause"); 2904 _worker_cset_start_region[worker_i] = result; 2905 OrderAccess::storestore(); 2906 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2907 return result; 2908 } 2909 2910 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2911 uint no_of_par_workers) { 2912 uint worker_num = 2913 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2914 assert(UseDynamicNumberOfGCThreads || 2915 no_of_par_workers == workers()->total_workers(), 2916 "Non dynamic should use fixed number of workers"); 2917 const uint start_index = n_regions() * worker_i / worker_num; 2918 return region_at(start_index); 2919 } 2920 2921 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2922 HeapRegion* r = g1_policy()->collection_set(); 2923 while (r != NULL) { 2924 HeapRegion* next = r->next_in_collection_set(); 2925 if (cl->doHeapRegion(r)) { 2926 cl->incomplete(); 2927 return; 2928 } 2929 r = next; 2930 } 2931 } 2932 2933 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2934 HeapRegionClosure *cl) { 2935 if (r == NULL) { 2936 // The CSet is empty so there's nothing to do. 2937 return; 2938 } 2939 2940 assert(r->in_collection_set(), 2941 "Start region must be a member of the collection set."); 2942 HeapRegion* cur = r; 2943 while (cur != NULL) { 2944 HeapRegion* next = cur->next_in_collection_set(); 2945 if (cl->doHeapRegion(cur) && false) { 2946 cl->incomplete(); 2947 return; 2948 } 2949 cur = next; 2950 } 2951 cur = g1_policy()->collection_set(); 2952 while (cur != r) { 2953 HeapRegion* next = cur->next_in_collection_set(); 2954 if (cl->doHeapRegion(cur) && false) { 2955 cl->incomplete(); 2956 return; 2957 } 2958 cur = next; 2959 } 2960 } 2961 2962 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2963 return n_regions() > 0 ? region_at(0) : NULL; 2964 } 2965 2966 2967 Space* G1CollectedHeap::space_containing(const void* addr) const { 2968 Space* res = heap_region_containing(addr); 2969 return res; 2970 } 2971 2972 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2973 Space* sp = space_containing(addr); 2974 if (sp != NULL) { 2975 return sp->block_start(addr); 2976 } 2977 return NULL; 2978 } 2979 2980 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2981 Space* sp = space_containing(addr); 2982 assert(sp != NULL, "block_size of address outside of heap"); 2983 return sp->block_size(addr); 2984 } 2985 2986 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2987 Space* sp = space_containing(addr); 2988 return sp->block_is_obj(addr); 2989 } 2990 2991 bool G1CollectedHeap::supports_tlab_allocation() const { 2992 return true; 2993 } 2994 2995 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2996 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2997 } 2998 2999 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 3000 return young_list()->eden_used_bytes(); 3001 } 3002 3003 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 3004 // must be smaller than the humongous object limit. 3005 size_t G1CollectedHeap::max_tlab_size() const { 3006 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 3007 } 3008 3009 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 3010 // Return the remaining space in the cur alloc region, but not less than 3011 // the min TLAB size. 3012 3013 // Also, this value can be at most the humongous object threshold, 3014 // since we can't allow tlabs to grow big enough to accommodate 3015 // humongous objects. 3016 3017 HeapRegion* hr = _mutator_alloc_region.get(); 3018 size_t max_tlab = max_tlab_size() * wordSize; 3019 if (hr == NULL) { 3020 return max_tlab; 3021 } else { 3022 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 3023 } 3024 } 3025 3026 size_t G1CollectedHeap::max_capacity() const { 3027 return _g1_reserved.byte_size(); 3028 } 3029 3030 jlong G1CollectedHeap::millis_since_last_gc() { 3031 // assert(false, "NYI"); 3032 return 0; 3033 } 3034 3035 void G1CollectedHeap::prepare_for_verify() { 3036 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3037 ensure_parsability(false); 3038 } 3039 g1_rem_set()->prepare_for_verify(); 3040 } 3041 3042 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3043 VerifyOption vo) { 3044 switch (vo) { 3045 case VerifyOption_G1UsePrevMarking: 3046 return hr->obj_allocated_since_prev_marking(obj); 3047 case VerifyOption_G1UseNextMarking: 3048 return hr->obj_allocated_since_next_marking(obj); 3049 case VerifyOption_G1UseMarkWord: 3050 return false; 3051 default: 3052 ShouldNotReachHere(); 3053 } 3054 return false; // keep some compilers happy 3055 } 3056 3057 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3058 switch (vo) { 3059 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3060 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3061 case VerifyOption_G1UseMarkWord: return NULL; 3062 default: ShouldNotReachHere(); 3063 } 3064 return NULL; // keep some compilers happy 3065 } 3066 3067 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3068 switch (vo) { 3069 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3070 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3071 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3072 default: ShouldNotReachHere(); 3073 } 3074 return false; // keep some compilers happy 3075 } 3076 3077 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3078 switch (vo) { 3079 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3080 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3081 case VerifyOption_G1UseMarkWord: return "NONE"; 3082 default: ShouldNotReachHere(); 3083 } 3084 return NULL; // keep some compilers happy 3085 } 3086 3087 class VerifyRootsClosure: public OopClosure { 3088 private: 3089 G1CollectedHeap* _g1h; 3090 VerifyOption _vo; 3091 bool _failures; 3092 public: 3093 // _vo == UsePrevMarking -> use "prev" marking information, 3094 // _vo == UseNextMarking -> use "next" marking information, 3095 // _vo == UseMarkWord -> use mark word from object header. 3096 VerifyRootsClosure(VerifyOption vo) : 3097 _g1h(G1CollectedHeap::heap()), 3098 _vo(vo), 3099 _failures(false) { } 3100 3101 bool failures() { return _failures; } 3102 3103 template <class T> void do_oop_nv(T* p) { 3104 T heap_oop = oopDesc::load_heap_oop(p); 3105 if (!oopDesc::is_null(heap_oop)) { 3106 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3107 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3108 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3109 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3110 if (_vo == VerifyOption_G1UseMarkWord) { 3111 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3112 } 3113 obj->print_on(gclog_or_tty); 3114 _failures = true; 3115 } 3116 } 3117 } 3118 3119 void do_oop(oop* p) { do_oop_nv(p); } 3120 void do_oop(narrowOop* p) { do_oop_nv(p); } 3121 }; 3122 3123 class G1VerifyCodeRootOopClosure: public OopClosure { 3124 G1CollectedHeap* _g1h; 3125 OopClosure* _root_cl; 3126 nmethod* _nm; 3127 VerifyOption _vo; 3128 bool _failures; 3129 3130 template <class T> void do_oop_work(T* p) { 3131 // First verify that this root is live 3132 _root_cl->do_oop(p); 3133 3134 if (!G1VerifyHeapRegionCodeRoots) { 3135 // We're not verifying the code roots attached to heap region. 3136 return; 3137 } 3138 3139 // Don't check the code roots during marking verification in a full GC 3140 if (_vo == VerifyOption_G1UseMarkWord) { 3141 return; 3142 } 3143 3144 // Now verify that the current nmethod (which contains p) is 3145 // in the code root list of the heap region containing the 3146 // object referenced by p. 3147 3148 T heap_oop = oopDesc::load_heap_oop(p); 3149 if (!oopDesc::is_null(heap_oop)) { 3150 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3151 3152 // Now fetch the region containing the object 3153 HeapRegion* hr = _g1h->heap_region_containing(obj); 3154 HeapRegionRemSet* hrrs = hr->rem_set(); 3155 // Verify that the strong code root list for this region 3156 // contains the nmethod 3157 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3158 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3159 "from nmethod "PTR_FORMAT" not in strong " 3160 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3161 p, _nm, hr->bottom(), hr->end()); 3162 _failures = true; 3163 } 3164 } 3165 } 3166 3167 public: 3168 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3169 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3170 3171 void do_oop(oop* p) { do_oop_work(p); } 3172 void do_oop(narrowOop* p) { do_oop_work(p); } 3173 3174 void set_nmethod(nmethod* nm) { _nm = nm; } 3175 bool failures() { return _failures; } 3176 }; 3177 3178 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3179 G1VerifyCodeRootOopClosure* _oop_cl; 3180 3181 public: 3182 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3183 _oop_cl(oop_cl) {} 3184 3185 void do_code_blob(CodeBlob* cb) { 3186 nmethod* nm = cb->as_nmethod_or_null(); 3187 if (nm != NULL) { 3188 _oop_cl->set_nmethod(nm); 3189 nm->oops_do(_oop_cl); 3190 } 3191 } 3192 }; 3193 3194 class YoungRefCounterClosure : public OopClosure { 3195 G1CollectedHeap* _g1h; 3196 int _count; 3197 public: 3198 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3199 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3200 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3201 3202 int count() { return _count; } 3203 void reset_count() { _count = 0; }; 3204 }; 3205 3206 class VerifyKlassClosure: public KlassClosure { 3207 YoungRefCounterClosure _young_ref_counter_closure; 3208 OopClosure *_oop_closure; 3209 public: 3210 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3211 void do_klass(Klass* k) { 3212 k->oops_do(_oop_closure); 3213 3214 _young_ref_counter_closure.reset_count(); 3215 k->oops_do(&_young_ref_counter_closure); 3216 if (_young_ref_counter_closure.count() > 0) { 3217 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k)); 3218 } 3219 } 3220 }; 3221 3222 class VerifyLivenessOopClosure: public OopClosure { 3223 G1CollectedHeap* _g1h; 3224 VerifyOption _vo; 3225 public: 3226 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3227 _g1h(g1h), _vo(vo) 3228 { } 3229 void do_oop(narrowOop *p) { do_oop_work(p); } 3230 void do_oop( oop *p) { do_oop_work(p); } 3231 3232 template <class T> void do_oop_work(T *p) { 3233 oop obj = oopDesc::load_decode_heap_oop(p); 3234 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3235 "Dead object referenced by a not dead object"); 3236 } 3237 }; 3238 3239 class VerifyObjsInRegionClosure: public ObjectClosure { 3240 private: 3241 G1CollectedHeap* _g1h; 3242 size_t _live_bytes; 3243 HeapRegion *_hr; 3244 VerifyOption _vo; 3245 public: 3246 // _vo == UsePrevMarking -> use "prev" marking information, 3247 // _vo == UseNextMarking -> use "next" marking information, 3248 // _vo == UseMarkWord -> use mark word from object header. 3249 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3250 : _live_bytes(0), _hr(hr), _vo(vo) { 3251 _g1h = G1CollectedHeap::heap(); 3252 } 3253 void do_object(oop o) { 3254 VerifyLivenessOopClosure isLive(_g1h, _vo); 3255 assert(o != NULL, "Huh?"); 3256 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3257 // If the object is alive according to the mark word, 3258 // then verify that the marking information agrees. 3259 // Note we can't verify the contra-positive of the 3260 // above: if the object is dead (according to the mark 3261 // word), it may not be marked, or may have been marked 3262 // but has since became dead, or may have been allocated 3263 // since the last marking. 3264 if (_vo == VerifyOption_G1UseMarkWord) { 3265 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3266 } 3267 3268 o->oop_iterate_no_header(&isLive); 3269 if (!_hr->obj_allocated_since_prev_marking(o)) { 3270 size_t obj_size = o->size(); // Make sure we don't overflow 3271 _live_bytes += (obj_size * HeapWordSize); 3272 } 3273 } 3274 } 3275 size_t live_bytes() { return _live_bytes; } 3276 }; 3277 3278 class PrintObjsInRegionClosure : public ObjectClosure { 3279 HeapRegion *_hr; 3280 G1CollectedHeap *_g1; 3281 public: 3282 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3283 _g1 = G1CollectedHeap::heap(); 3284 }; 3285 3286 void do_object(oop o) { 3287 if (o != NULL) { 3288 HeapWord *start = (HeapWord *) o; 3289 size_t word_sz = o->size(); 3290 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3291 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3292 (void*) o, word_sz, 3293 _g1->isMarkedPrev(o), 3294 _g1->isMarkedNext(o), 3295 _hr->obj_allocated_since_prev_marking(o)); 3296 HeapWord *end = start + word_sz; 3297 HeapWord *cur; 3298 int *val; 3299 for (cur = start; cur < end; cur++) { 3300 val = (int *) cur; 3301 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3302 } 3303 } 3304 } 3305 }; 3306 3307 class VerifyRegionClosure: public HeapRegionClosure { 3308 private: 3309 bool _par; 3310 VerifyOption _vo; 3311 bool _failures; 3312 public: 3313 // _vo == UsePrevMarking -> use "prev" marking information, 3314 // _vo == UseNextMarking -> use "next" marking information, 3315 // _vo == UseMarkWord -> use mark word from object header. 3316 VerifyRegionClosure(bool par, VerifyOption vo) 3317 : _par(par), 3318 _vo(vo), 3319 _failures(false) {} 3320 3321 bool failures() { 3322 return _failures; 3323 } 3324 3325 bool doHeapRegion(HeapRegion* r) { 3326 if (!r->continuesHumongous()) { 3327 bool failures = false; 3328 r->verify(_vo, &failures); 3329 if (failures) { 3330 _failures = true; 3331 } else { 3332 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3333 r->object_iterate(¬_dead_yet_cl); 3334 if (_vo != VerifyOption_G1UseNextMarking) { 3335 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3336 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3337 "max_live_bytes "SIZE_FORMAT" " 3338 "< calculated "SIZE_FORMAT, 3339 r->bottom(), r->end(), 3340 r->max_live_bytes(), 3341 not_dead_yet_cl.live_bytes()); 3342 _failures = true; 3343 } 3344 } else { 3345 // When vo == UseNextMarking we cannot currently do a sanity 3346 // check on the live bytes as the calculation has not been 3347 // finalized yet. 3348 } 3349 } 3350 } 3351 return false; // stop the region iteration if we hit a failure 3352 } 3353 }; 3354 3355 // This is the task used for parallel verification of the heap regions 3356 3357 class G1ParVerifyTask: public AbstractGangTask { 3358 private: 3359 G1CollectedHeap* _g1h; 3360 VerifyOption _vo; 3361 bool _failures; 3362 3363 public: 3364 // _vo == UsePrevMarking -> use "prev" marking information, 3365 // _vo == UseNextMarking -> use "next" marking information, 3366 // _vo == UseMarkWord -> use mark word from object header. 3367 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3368 AbstractGangTask("Parallel verify task"), 3369 _g1h(g1h), 3370 _vo(vo), 3371 _failures(false) { } 3372 3373 bool failures() { 3374 return _failures; 3375 } 3376 3377 void work(uint worker_id) { 3378 HandleMark hm; 3379 VerifyRegionClosure blk(true, _vo); 3380 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3381 _g1h->workers()->active_workers(), 3382 HeapRegion::ParVerifyClaimValue); 3383 if (blk.failures()) { 3384 _failures = true; 3385 } 3386 } 3387 }; 3388 3389 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3390 if (SafepointSynchronize::is_at_safepoint()) { 3391 assert(Thread::current()->is_VM_thread(), 3392 "Expected to be executed serially by the VM thread at this point"); 3393 3394 if (!silent) { gclog_or_tty->print("Roots "); } 3395 VerifyRootsClosure rootsCl(vo); 3396 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3397 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3398 VerifyKlassClosure klassCl(this, &rootsCl); 3399 3400 // We apply the relevant closures to all the oops in the 3401 // system dictionary, the string table and the code cache. 3402 const int so = SO_AllClasses | SO_Strings | SO_AllCodeCache; 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 &blobsCl, 3411 &klassCl 3412 ); 3413 3414 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3415 3416 if (vo != VerifyOption_G1UseMarkWord) { 3417 // If we're verifying during a full GC then the region sets 3418 // will have been torn down at the start of the GC. Therefore 3419 // verifying the region sets will fail. So we only verify 3420 // the region sets when not in a full GC. 3421 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3422 verify_region_sets(); 3423 } 3424 3425 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3426 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3427 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3428 "sanity check"); 3429 3430 G1ParVerifyTask task(this, vo); 3431 assert(UseDynamicNumberOfGCThreads || 3432 workers()->active_workers() == workers()->total_workers(), 3433 "If not dynamic should be using all the workers"); 3434 int n_workers = workers()->active_workers(); 3435 set_par_threads(n_workers); 3436 workers()->run_task(&task); 3437 set_par_threads(0); 3438 if (task.failures()) { 3439 failures = true; 3440 } 3441 3442 // Checks that the expected amount of parallel work was done. 3443 // The implication is that n_workers is > 0. 3444 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3445 "sanity check"); 3446 3447 reset_heap_region_claim_values(); 3448 3449 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3450 "sanity check"); 3451 } else { 3452 VerifyRegionClosure blk(false, vo); 3453 heap_region_iterate(&blk); 3454 if (blk.failures()) { 3455 failures = true; 3456 } 3457 } 3458 if (!silent) gclog_or_tty->print("RemSet "); 3459 rem_set()->verify(); 3460 3461 if (failures) { 3462 gclog_or_tty->print_cr("Heap:"); 3463 // It helps to have the per-region information in the output to 3464 // help us track down what went wrong. This is why we call 3465 // print_extended_on() instead of print_on(). 3466 print_extended_on(gclog_or_tty); 3467 gclog_or_tty->print_cr(""); 3468 #ifndef PRODUCT 3469 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3470 concurrent_mark()->print_reachable("at-verification-failure", 3471 vo, false /* all */); 3472 } 3473 #endif 3474 gclog_or_tty->flush(); 3475 } 3476 guarantee(!failures, "there should not have been any failures"); 3477 } else { 3478 if (!silent) 3479 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) "); 3480 } 3481 } 3482 3483 void G1CollectedHeap::verify(bool silent) { 3484 verify(silent, VerifyOption_G1UsePrevMarking); 3485 } 3486 3487 double G1CollectedHeap::verify(bool guard, const char* msg) { 3488 double verify_time_ms = 0.0; 3489 3490 if (guard && total_collections() >= VerifyGCStartAt) { 3491 double verify_start = os::elapsedTime(); 3492 HandleMark hm; // Discard invalid handles created during verification 3493 prepare_for_verify(); 3494 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3495 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3496 } 3497 3498 return verify_time_ms; 3499 } 3500 3501 void G1CollectedHeap::verify_before_gc() { 3502 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3503 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3504 } 3505 3506 void G1CollectedHeap::verify_after_gc() { 3507 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3508 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3509 } 3510 3511 class PrintRegionClosure: public HeapRegionClosure { 3512 outputStream* _st; 3513 public: 3514 PrintRegionClosure(outputStream* st) : _st(st) {} 3515 bool doHeapRegion(HeapRegion* r) { 3516 r->print_on(_st); 3517 return false; 3518 } 3519 }; 3520 3521 void G1CollectedHeap::print_on(outputStream* st) const { 3522 st->print(" %-20s", "garbage-first heap"); 3523 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3524 capacity()/K, used_unlocked()/K); 3525 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3526 _g1_storage.low_boundary(), 3527 _g1_storage.high(), 3528 _g1_storage.high_boundary()); 3529 st->cr(); 3530 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3531 uint young_regions = _young_list->length(); 3532 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3533 (size_t) young_regions * HeapRegion::GrainBytes / K); 3534 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3535 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3536 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3537 st->cr(); 3538 MetaspaceAux::print_on(st); 3539 } 3540 3541 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3542 print_on(st); 3543 3544 // Print the per-region information. 3545 st->cr(); 3546 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3547 "HS=humongous(starts), HC=humongous(continues), " 3548 "CS=collection set, F=free, TS=gc time stamp, " 3549 "PTAMS=previous top-at-mark-start, " 3550 "NTAMS=next top-at-mark-start)"); 3551 PrintRegionClosure blk(st); 3552 heap_region_iterate(&blk); 3553 } 3554 3555 void G1CollectedHeap::print_on_error(outputStream* st) const { 3556 this->CollectedHeap::print_on_error(st); 3557 3558 if (_cm != NULL) { 3559 st->cr(); 3560 _cm->print_on_error(st); 3561 } 3562 } 3563 3564 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3565 if (G1CollectedHeap::use_parallel_gc_threads()) { 3566 workers()->print_worker_threads_on(st); 3567 } 3568 _cmThread->print_on(st); 3569 st->cr(); 3570 _cm->print_worker_threads_on(st); 3571 _cg1r->print_worker_threads_on(st); 3572 } 3573 3574 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3575 if (G1CollectedHeap::use_parallel_gc_threads()) { 3576 workers()->threads_do(tc); 3577 } 3578 tc->do_thread(_cmThread); 3579 _cg1r->threads_do(tc); 3580 } 3581 3582 void G1CollectedHeap::print_tracing_info() const { 3583 // We'll overload this to mean "trace GC pause statistics." 3584 if (TraceGen0Time || TraceGen1Time) { 3585 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3586 // to that. 3587 g1_policy()->print_tracing_info(); 3588 } 3589 if (G1SummarizeRSetStats) { 3590 g1_rem_set()->print_summary_info(); 3591 } 3592 if (G1SummarizeConcMark) { 3593 concurrent_mark()->print_summary_info(); 3594 } 3595 g1_policy()->print_yg_surv_rate_info(); 3596 SpecializationStats::print(); 3597 } 3598 3599 #ifndef PRODUCT 3600 // Helpful for debugging RSet issues. 3601 3602 class PrintRSetsClosure : public HeapRegionClosure { 3603 private: 3604 const char* _msg; 3605 size_t _occupied_sum; 3606 3607 public: 3608 bool doHeapRegion(HeapRegion* r) { 3609 HeapRegionRemSet* hrrs = r->rem_set(); 3610 size_t occupied = hrrs->occupied(); 3611 _occupied_sum += occupied; 3612 3613 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3614 HR_FORMAT_PARAMS(r)); 3615 if (occupied == 0) { 3616 gclog_or_tty->print_cr(" RSet is empty"); 3617 } else { 3618 hrrs->print(); 3619 } 3620 gclog_or_tty->print_cr("----------"); 3621 return false; 3622 } 3623 3624 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3625 gclog_or_tty->cr(); 3626 gclog_or_tty->print_cr("========================================"); 3627 gclog_or_tty->print_cr(msg); 3628 gclog_or_tty->cr(); 3629 } 3630 3631 ~PrintRSetsClosure() { 3632 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3633 gclog_or_tty->print_cr("========================================"); 3634 gclog_or_tty->cr(); 3635 } 3636 }; 3637 3638 void G1CollectedHeap::print_cset_rsets() { 3639 PrintRSetsClosure cl("Printing CSet RSets"); 3640 collection_set_iterate(&cl); 3641 } 3642 3643 void G1CollectedHeap::print_all_rsets() { 3644 PrintRSetsClosure cl("Printing All RSets");; 3645 heap_region_iterate(&cl); 3646 } 3647 #endif // PRODUCT 3648 3649 G1CollectedHeap* G1CollectedHeap::heap() { 3650 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3651 "not a garbage-first heap"); 3652 return _g1h; 3653 } 3654 3655 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3656 // always_do_update_barrier = false; 3657 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3658 // Fill TLAB's and such 3659 accumulate_statistics_all_tlabs(); 3660 ensure_parsability(true); 3661 3662 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3663 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3664 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3665 } 3666 } 3667 3668 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3669 3670 if (G1SummarizeRSetStats && 3671 (G1SummarizeRSetStatsPeriod > 0) && 3672 // we are at the end of the GC. Total collections has already been increased. 3673 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3674 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3675 } 3676 3677 // FIXME: what is this about? 3678 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3679 // is set. 3680 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3681 "derived pointer present")); 3682 // always_do_update_barrier = true; 3683 3684 resize_all_tlabs(); 3685 3686 // We have just completed a GC. Update the soft reference 3687 // policy with the new heap occupancy 3688 Universe::update_heap_info_at_gc(); 3689 } 3690 3691 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3692 unsigned int gc_count_before, 3693 bool* succeeded, 3694 GCCause::Cause gc_cause) { 3695 assert_heap_not_locked_and_not_at_safepoint(); 3696 g1_policy()->record_stop_world_start(); 3697 VM_G1IncCollectionPause op(gc_count_before, 3698 word_size, 3699 false, /* should_initiate_conc_mark */ 3700 g1_policy()->max_pause_time_ms(), 3701 gc_cause); 3702 VMThread::execute(&op); 3703 3704 HeapWord* result = op.result(); 3705 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3706 assert(result == NULL || ret_succeeded, 3707 "the result should be NULL if the VM did not succeed"); 3708 *succeeded = ret_succeeded; 3709 3710 assert_heap_not_locked(); 3711 return result; 3712 } 3713 3714 void 3715 G1CollectedHeap::doConcurrentMark() { 3716 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3717 if (!_cmThread->in_progress()) { 3718 _cmThread->set_started(); 3719 CGC_lock->notify(); 3720 } 3721 } 3722 3723 size_t G1CollectedHeap::pending_card_num() { 3724 size_t extra_cards = 0; 3725 JavaThread *curr = Threads::first(); 3726 while (curr != NULL) { 3727 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3728 extra_cards += dcq.size(); 3729 curr = curr->next(); 3730 } 3731 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3732 size_t buffer_size = dcqs.buffer_size(); 3733 size_t buffer_num = dcqs.completed_buffers_num(); 3734 3735 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3736 // in bytes - not the number of 'entries'. We need to convert 3737 // into a number of cards. 3738 return (buffer_size * buffer_num + extra_cards) / oopSize; 3739 } 3740 3741 size_t G1CollectedHeap::cards_scanned() { 3742 return g1_rem_set()->cardsScanned(); 3743 } 3744 3745 void 3746 G1CollectedHeap::setup_surviving_young_words() { 3747 assert(_surviving_young_words == NULL, "pre-condition"); 3748 uint array_length = g1_policy()->young_cset_region_length(); 3749 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3750 if (_surviving_young_words == NULL) { 3751 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3752 "Not enough space for young surv words summary."); 3753 } 3754 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3755 #ifdef ASSERT 3756 for (uint i = 0; i < array_length; ++i) { 3757 assert( _surviving_young_words[i] == 0, "memset above" ); 3758 } 3759 #endif // !ASSERT 3760 } 3761 3762 void 3763 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3764 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3765 uint array_length = g1_policy()->young_cset_region_length(); 3766 for (uint i = 0; i < array_length; ++i) { 3767 _surviving_young_words[i] += surv_young_words[i]; 3768 } 3769 } 3770 3771 void 3772 G1CollectedHeap::cleanup_surviving_young_words() { 3773 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3774 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3775 _surviving_young_words = NULL; 3776 } 3777 3778 #ifdef ASSERT 3779 class VerifyCSetClosure: public HeapRegionClosure { 3780 public: 3781 bool doHeapRegion(HeapRegion* hr) { 3782 // Here we check that the CSet region's RSet is ready for parallel 3783 // iteration. The fields that we'll verify are only manipulated 3784 // when the region is part of a CSet and is collected. Afterwards, 3785 // we reset these fields when we clear the region's RSet (when the 3786 // region is freed) so they are ready when the region is 3787 // re-allocated. The only exception to this is if there's an 3788 // evacuation failure and instead of freeing the region we leave 3789 // it in the heap. In that case, we reset these fields during 3790 // evacuation failure handling. 3791 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3792 3793 // Here's a good place to add any other checks we'd like to 3794 // perform on CSet regions. 3795 return false; 3796 } 3797 }; 3798 #endif // ASSERT 3799 3800 #if TASKQUEUE_STATS 3801 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3802 st->print_raw_cr("GC Task Stats"); 3803 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3804 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3805 } 3806 3807 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3808 print_taskqueue_stats_hdr(st); 3809 3810 TaskQueueStats totals; 3811 const int n = workers() != NULL ? workers()->total_workers() : 1; 3812 for (int i = 0; i < n; ++i) { 3813 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3814 totals += task_queue(i)->stats; 3815 } 3816 st->print_raw("tot "); totals.print(st); st->cr(); 3817 3818 DEBUG_ONLY(totals.verify()); 3819 } 3820 3821 void G1CollectedHeap::reset_taskqueue_stats() { 3822 const int n = workers() != NULL ? workers()->total_workers() : 1; 3823 for (int i = 0; i < n; ++i) { 3824 task_queue(i)->stats.reset(); 3825 } 3826 } 3827 #endif // TASKQUEUE_STATS 3828 3829 void G1CollectedHeap::log_gc_header() { 3830 if (!G1Log::fine()) { 3831 return; 3832 } 3833 3834 gclog_or_tty->date_stamp(PrintGCDateStamps); 3835 gclog_or_tty->stamp(PrintGCTimeStamps); 3836 3837 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3838 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3839 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3840 3841 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3842 } 3843 3844 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3845 if (!G1Log::fine()) { 3846 return; 3847 } 3848 3849 if (G1Log::finer()) { 3850 if (evacuation_failed()) { 3851 gclog_or_tty->print(" (to-space exhausted)"); 3852 } 3853 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3854 g1_policy()->phase_times()->note_gc_end(); 3855 g1_policy()->phase_times()->print(pause_time_sec); 3856 g1_policy()->print_detailed_heap_transition(); 3857 } else { 3858 if (evacuation_failed()) { 3859 gclog_or_tty->print("--"); 3860 } 3861 g1_policy()->print_heap_transition(); 3862 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3863 } 3864 gclog_or_tty->flush(); 3865 } 3866 3867 bool 3868 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3869 assert_at_safepoint(true /* should_be_vm_thread */); 3870 guarantee(!is_gc_active(), "collection is not reentrant"); 3871 3872 if (GC_locker::check_active_before_gc()) { 3873 return false; 3874 } 3875 3876 _gc_timer_stw->register_gc_start(); 3877 3878 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3879 3880 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3881 ResourceMark rm; 3882 3883 print_heap_before_gc(); 3884 trace_heap_before_gc(_gc_tracer_stw); 3885 3886 verify_region_sets_optional(); 3887 verify_dirty_young_regions(); 3888 3889 // This call will decide whether this pause is an initial-mark 3890 // pause. If it is, during_initial_mark_pause() will return true 3891 // for the duration of this pause. 3892 g1_policy()->decide_on_conc_mark_initiation(); 3893 3894 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3895 assert(!g1_policy()->during_initial_mark_pause() || 3896 g1_policy()->gcs_are_young(), "sanity"); 3897 3898 // We also do not allow mixed GCs during marking. 3899 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3900 3901 // Record whether this pause is an initial mark. When the current 3902 // thread has completed its logging output and it's safe to signal 3903 // the CM thread, the flag's value in the policy has been reset. 3904 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3905 3906 // Inner scope for scope based logging, timers, and stats collection 3907 { 3908 EvacuationInfo evacuation_info; 3909 3910 if (g1_policy()->during_initial_mark_pause()) { 3911 // We are about to start a marking cycle, so we increment the 3912 // full collection counter. 3913 increment_old_marking_cycles_started(); 3914 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3915 } 3916 3917 _gc_tracer_stw->report_yc_type(yc_type()); 3918 3919 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3920 3921 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3922 workers()->active_workers() : 1); 3923 double pause_start_sec = os::elapsedTime(); 3924 g1_policy()->phase_times()->note_gc_start(active_workers); 3925 log_gc_header(); 3926 3927 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3928 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3929 3930 // If the secondary_free_list is not empty, append it to the 3931 // free_list. No need to wait for the cleanup operation to finish; 3932 // the region allocation code will check the secondary_free_list 3933 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3934 // set, skip this step so that the region allocation code has to 3935 // get entries from the secondary_free_list. 3936 if (!G1StressConcRegionFreeing) { 3937 append_secondary_free_list_if_not_empty_with_lock(); 3938 } 3939 3940 assert(check_young_list_well_formed(), "young list should be well formed"); 3941 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3942 "sanity check"); 3943 3944 // Don't dynamically change the number of GC threads this early. A value of 3945 // 0 is used to indicate serial work. When parallel work is done, 3946 // it will be set. 3947 3948 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3949 IsGCActiveMark x; 3950 3951 gc_prologue(false); 3952 increment_total_collections(false /* full gc */); 3953 increment_gc_time_stamp(); 3954 3955 verify_before_gc(); 3956 3957 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3958 3959 // Please see comment in g1CollectedHeap.hpp and 3960 // G1CollectedHeap::ref_processing_init() to see how 3961 // reference processing currently works in G1. 3962 3963 // Enable discovery in the STW reference processor 3964 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3965 true /*verify_no_refs*/); 3966 3967 { 3968 // We want to temporarily turn off discovery by the 3969 // CM ref processor, if necessary, and turn it back on 3970 // on again later if we do. Using a scoped 3971 // NoRefDiscovery object will do this. 3972 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3973 3974 // Forget the current alloc region (we might even choose it to be part 3975 // of the collection set!). 3976 release_mutator_alloc_region(); 3977 3978 // We should call this after we retire the mutator alloc 3979 // region(s) so that all the ALLOC / RETIRE events are generated 3980 // before the start GC event. 3981 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3982 3983 // This timing is only used by the ergonomics to handle our pause target. 3984 // It is unclear why this should not include the full pause. We will 3985 // investigate this in CR 7178365. 3986 // 3987 // Preserving the old comment here if that helps the investigation: 3988 // 3989 // The elapsed time induced by the start time below deliberately elides 3990 // the possible verification above. 3991 double sample_start_time_sec = os::elapsedTime(); 3992 3993 #if YOUNG_LIST_VERBOSE 3994 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3995 _young_list->print(); 3996 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3997 #endif // YOUNG_LIST_VERBOSE 3998 3999 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4000 4001 double scan_wait_start = os::elapsedTime(); 4002 // We have to wait until the CM threads finish scanning the 4003 // root regions as it's the only way to ensure that all the 4004 // objects on them have been correctly scanned before we start 4005 // moving them during the GC. 4006 bool waited = _cm->root_regions()->wait_until_scan_finished(); 4007 double wait_time_ms = 0.0; 4008 if (waited) { 4009 double scan_wait_end = os::elapsedTime(); 4010 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4011 } 4012 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4013 4014 #if YOUNG_LIST_VERBOSE 4015 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4016 _young_list->print(); 4017 #endif // YOUNG_LIST_VERBOSE 4018 4019 if (g1_policy()->during_initial_mark_pause()) { 4020 concurrent_mark()->checkpointRootsInitialPre(); 4021 } 4022 4023 #if YOUNG_LIST_VERBOSE 4024 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4025 _young_list->print(); 4026 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4027 #endif // YOUNG_LIST_VERBOSE 4028 4029 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4030 4031 _cm->note_start_of_gc(); 4032 // We should not verify the per-thread SATB buffers given that 4033 // we have not filtered them yet (we'll do so during the 4034 // GC). We also call this after finalize_cset() to 4035 // ensure that the CSet has been finalized. 4036 _cm->verify_no_cset_oops(true /* verify_stacks */, 4037 true /* verify_enqueued_buffers */, 4038 false /* verify_thread_buffers */, 4039 true /* verify_fingers */); 4040 4041 if (_hr_printer.is_active()) { 4042 HeapRegion* hr = g1_policy()->collection_set(); 4043 while (hr != NULL) { 4044 G1HRPrinter::RegionType type; 4045 if (!hr->is_young()) { 4046 type = G1HRPrinter::Old; 4047 } else if (hr->is_survivor()) { 4048 type = G1HRPrinter::Survivor; 4049 } else { 4050 type = G1HRPrinter::Eden; 4051 } 4052 _hr_printer.cset(hr); 4053 hr = hr->next_in_collection_set(); 4054 } 4055 } 4056 4057 #ifdef ASSERT 4058 VerifyCSetClosure cl; 4059 collection_set_iterate(&cl); 4060 #endif // ASSERT 4061 4062 setup_surviving_young_words(); 4063 4064 // Initialize the GC alloc regions. 4065 init_gc_alloc_regions(evacuation_info); 4066 4067 // Actually do the work... 4068 evacuate_collection_set(evacuation_info); 4069 4070 // We do this to mainly verify the per-thread SATB buffers 4071 // (which have been filtered by now) since we didn't verify 4072 // them earlier. No point in re-checking the stacks / enqueued 4073 // buffers given that the CSet has not changed since last time 4074 // we checked. 4075 _cm->verify_no_cset_oops(false /* verify_stacks */, 4076 false /* verify_enqueued_buffers */, 4077 true /* verify_thread_buffers */, 4078 true /* verify_fingers */); 4079 4080 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4081 g1_policy()->clear_collection_set(); 4082 4083 cleanup_surviving_young_words(); 4084 4085 // Start a new incremental collection set for the next pause. 4086 g1_policy()->start_incremental_cset_building(); 4087 4088 // Clear the _cset_fast_test bitmap in anticipation of adding 4089 // regions to the incremental collection set for the next 4090 // evacuation pause. 4091 clear_cset_fast_test(); 4092 4093 _young_list->reset_sampled_info(); 4094 4095 // Don't check the whole heap at this point as the 4096 // GC alloc regions from this pause have been tagged 4097 // as survivors and moved on to the survivor list. 4098 // Survivor regions will fail the !is_young() check. 4099 assert(check_young_list_empty(false /* check_heap */), 4100 "young list should be empty"); 4101 4102 #if YOUNG_LIST_VERBOSE 4103 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4104 _young_list->print(); 4105 #endif // YOUNG_LIST_VERBOSE 4106 4107 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4108 _young_list->first_survivor_region(), 4109 _young_list->last_survivor_region()); 4110 4111 _young_list->reset_auxilary_lists(); 4112 4113 if (evacuation_failed()) { 4114 _summary_bytes_used = recalculate_used(); 4115 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4116 for (uint i = 0; i < n_queues; i++) { 4117 if (_evacuation_failed_info_array[i].has_failed()) { 4118 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4119 } 4120 } 4121 } else { 4122 // The "used" of the the collection set have already been subtracted 4123 // when they were freed. Add in the bytes evacuated. 4124 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4125 } 4126 4127 if (g1_policy()->during_initial_mark_pause()) { 4128 // We have to do this before we notify the CM threads that 4129 // they can start working to make sure that all the 4130 // appropriate initialization is done on the CM object. 4131 concurrent_mark()->checkpointRootsInitialPost(); 4132 set_marking_started(); 4133 // Note that we don't actually trigger the CM thread at 4134 // this point. We do that later when we're sure that 4135 // the current thread has completed its logging output. 4136 } 4137 4138 allocate_dummy_regions(); 4139 4140 #if YOUNG_LIST_VERBOSE 4141 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4142 _young_list->print(); 4143 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4144 #endif // YOUNG_LIST_VERBOSE 4145 4146 init_mutator_alloc_region(); 4147 4148 { 4149 size_t expand_bytes = g1_policy()->expansion_amount(); 4150 if (expand_bytes > 0) { 4151 size_t bytes_before = capacity(); 4152 // No need for an ergo verbose message here, 4153 // expansion_amount() does this when it returns a value > 0. 4154 if (!expand(expand_bytes)) { 4155 // We failed to expand the heap so let's verify that 4156 // committed/uncommitted amount match the backing store 4157 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4158 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4159 } 4160 } 4161 } 4162 4163 // We redo the verification but now wrt to the new CSet which 4164 // has just got initialized after the previous CSet was freed. 4165 _cm->verify_no_cset_oops(true /* verify_stacks */, 4166 true /* verify_enqueued_buffers */, 4167 true /* verify_thread_buffers */, 4168 true /* verify_fingers */); 4169 _cm->note_end_of_gc(); 4170 4171 // This timing is only used by the ergonomics to handle our pause target. 4172 // It is unclear why this should not include the full pause. We will 4173 // investigate this in CR 7178365. 4174 double sample_end_time_sec = os::elapsedTime(); 4175 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4176 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4177 4178 MemoryService::track_memory_usage(); 4179 4180 // In prepare_for_verify() below we'll need to scan the deferred 4181 // update buffers to bring the RSets up-to-date if 4182 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4183 // the update buffers we'll probably need to scan cards on the 4184 // regions we just allocated to (i.e., the GC alloc 4185 // regions). However, during the last GC we called 4186 // set_saved_mark() on all the GC alloc regions, so card 4187 // scanning might skip the [saved_mark_word()...top()] area of 4188 // those regions (i.e., the area we allocated objects into 4189 // during the last GC). But it shouldn't. Given that 4190 // saved_mark_word() is conditional on whether the GC time stamp 4191 // on the region is current or not, by incrementing the GC time 4192 // stamp here we invalidate all the GC time stamps on all the 4193 // regions and saved_mark_word() will simply return top() for 4194 // all the regions. This is a nicer way of ensuring this rather 4195 // than iterating over the regions and fixing them. In fact, the 4196 // GC time stamp increment here also ensures that 4197 // saved_mark_word() will return top() between pauses, i.e., 4198 // during concurrent refinement. So we don't need the 4199 // is_gc_active() check to decided which top to use when 4200 // scanning cards (see CR 7039627). 4201 increment_gc_time_stamp(); 4202 4203 verify_after_gc(); 4204 4205 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4206 ref_processor_stw()->verify_no_references_recorded(); 4207 4208 // CM reference discovery will be re-enabled if necessary. 4209 } 4210 4211 // We should do this after we potentially expand the heap so 4212 // that all the COMMIT events are generated before the end GC 4213 // event, and after we retire the GC alloc regions so that all 4214 // RETIRE events are generated before the end GC event. 4215 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4216 4217 if (mark_in_progress()) { 4218 concurrent_mark()->update_g1_committed(); 4219 } 4220 4221 #ifdef TRACESPINNING 4222 ParallelTaskTerminator::print_termination_counts(); 4223 #endif 4224 4225 gc_epilogue(false); 4226 } 4227 4228 // Print the remainder of the GC log output. 4229 log_gc_footer(os::elapsedTime() - pause_start_sec); 4230 4231 // It is not yet to safe to tell the concurrent mark to 4232 // start as we have some optional output below. We don't want the 4233 // output from the concurrent mark thread interfering with this 4234 // logging output either. 4235 4236 _hrs.verify_optional(); 4237 verify_region_sets_optional(); 4238 4239 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4240 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4241 4242 print_heap_after_gc(); 4243 trace_heap_after_gc(_gc_tracer_stw); 4244 4245 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4246 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4247 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4248 // before any GC notifications are raised. 4249 g1mm()->update_sizes(); 4250 4251 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4252 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4253 _gc_timer_stw->register_gc_end(); 4254 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4255 } 4256 // It should now be safe to tell the concurrent mark thread to start 4257 // without its logging output interfering with the logging output 4258 // that came from the pause. 4259 4260 if (should_start_conc_mark) { 4261 // CAUTION: after the doConcurrentMark() call below, 4262 // the concurrent marking thread(s) could be running 4263 // concurrently with us. Make sure that anything after 4264 // this point does not assume that we are the only GC thread 4265 // running. Note: of course, the actual marking work will 4266 // not start until the safepoint itself is released in 4267 // ConcurrentGCThread::safepoint_desynchronize(). 4268 doConcurrentMark(); 4269 } 4270 4271 return true; 4272 } 4273 4274 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4275 { 4276 size_t gclab_word_size; 4277 switch (purpose) { 4278 case GCAllocForSurvived: 4279 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4280 break; 4281 case GCAllocForTenured: 4282 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4283 break; 4284 default: 4285 assert(false, "unknown GCAllocPurpose"); 4286 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4287 break; 4288 } 4289 4290 // Prevent humongous PLAB sizes for two reasons: 4291 // * PLABs are allocated using a similar paths as oops, but should 4292 // never be in a humongous region 4293 // * Allowing humongous PLABs needlessly churns the region free lists 4294 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4295 } 4296 4297 void G1CollectedHeap::init_mutator_alloc_region() { 4298 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4299 _mutator_alloc_region.init(); 4300 } 4301 4302 void G1CollectedHeap::release_mutator_alloc_region() { 4303 _mutator_alloc_region.release(); 4304 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4305 } 4306 4307 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4308 assert_at_safepoint(true /* should_be_vm_thread */); 4309 4310 _survivor_gc_alloc_region.init(); 4311 _old_gc_alloc_region.init(); 4312 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4313 _retained_old_gc_alloc_region = NULL; 4314 4315 // We will discard the current GC alloc region if: 4316 // a) it's in the collection set (it can happen!), 4317 // b) it's already full (no point in using it), 4318 // c) it's empty (this means that it was emptied during 4319 // a cleanup and it should be on the free list now), or 4320 // d) it's humongous (this means that it was emptied 4321 // during a cleanup and was added to the free list, but 4322 // has been subsequently used to allocate a humongous 4323 // object that may be less than the region size). 4324 if (retained_region != NULL && 4325 !retained_region->in_collection_set() && 4326 !(retained_region->top() == retained_region->end()) && 4327 !retained_region->is_empty() && 4328 !retained_region->isHumongous()) { 4329 retained_region->set_saved_mark(); 4330 // The retained region was added to the old region set when it was 4331 // retired. We have to remove it now, since we don't allow regions 4332 // we allocate to in the region sets. We'll re-add it later, when 4333 // it's retired again. 4334 _old_set.remove(retained_region); 4335 bool during_im = g1_policy()->during_initial_mark_pause(); 4336 retained_region->note_start_of_copying(during_im); 4337 _old_gc_alloc_region.set(retained_region); 4338 _hr_printer.reuse(retained_region); 4339 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4340 } 4341 } 4342 4343 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4344 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4345 _old_gc_alloc_region.count()); 4346 _survivor_gc_alloc_region.release(); 4347 // If we have an old GC alloc region to release, we'll save it in 4348 // _retained_old_gc_alloc_region. If we don't 4349 // _retained_old_gc_alloc_region will become NULL. This is what we 4350 // want either way so no reason to check explicitly for either 4351 // condition. 4352 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4353 4354 if (ResizePLAB) { 4355 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4356 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4357 } 4358 } 4359 4360 void G1CollectedHeap::abandon_gc_alloc_regions() { 4361 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4362 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4363 _retained_old_gc_alloc_region = NULL; 4364 } 4365 4366 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4367 _drain_in_progress = false; 4368 set_evac_failure_closure(cl); 4369 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4370 } 4371 4372 void G1CollectedHeap::finalize_for_evac_failure() { 4373 assert(_evac_failure_scan_stack != NULL && 4374 _evac_failure_scan_stack->length() == 0, 4375 "Postcondition"); 4376 assert(!_drain_in_progress, "Postcondition"); 4377 delete _evac_failure_scan_stack; 4378 _evac_failure_scan_stack = NULL; 4379 } 4380 4381 void G1CollectedHeap::remove_self_forwarding_pointers() { 4382 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4383 4384 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4385 4386 if (G1CollectedHeap::use_parallel_gc_threads()) { 4387 set_par_threads(); 4388 workers()->run_task(&rsfp_task); 4389 set_par_threads(0); 4390 } else { 4391 rsfp_task.work(0); 4392 } 4393 4394 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4395 4396 // Reset the claim values in the regions in the collection set. 4397 reset_cset_heap_region_claim_values(); 4398 4399 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4400 4401 // Now restore saved marks, if any. 4402 assert(_objs_with_preserved_marks.size() == 4403 _preserved_marks_of_objs.size(), "Both or none."); 4404 while (!_objs_with_preserved_marks.is_empty()) { 4405 oop obj = _objs_with_preserved_marks.pop(); 4406 markOop m = _preserved_marks_of_objs.pop(); 4407 obj->set_mark(m); 4408 } 4409 _objs_with_preserved_marks.clear(true); 4410 _preserved_marks_of_objs.clear(true); 4411 } 4412 4413 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4414 _evac_failure_scan_stack->push(obj); 4415 } 4416 4417 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4418 assert(_evac_failure_scan_stack != NULL, "precondition"); 4419 4420 while (_evac_failure_scan_stack->length() > 0) { 4421 oop obj = _evac_failure_scan_stack->pop(); 4422 _evac_failure_closure->set_region(heap_region_containing(obj)); 4423 obj->oop_iterate_backwards(_evac_failure_closure); 4424 } 4425 } 4426 4427 oop 4428 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4429 oop old) { 4430 assert(obj_in_cs(old), 4431 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4432 (HeapWord*) old)); 4433 markOop m = old->mark(); 4434 oop forward_ptr = old->forward_to_atomic(old); 4435 if (forward_ptr == NULL) { 4436 // Forward-to-self succeeded. 4437 assert(_par_scan_state != NULL, "par scan state"); 4438 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4439 uint queue_num = _par_scan_state->queue_num(); 4440 4441 _evacuation_failed = true; 4442 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4443 if (_evac_failure_closure != cl) { 4444 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4445 assert(!_drain_in_progress, 4446 "Should only be true while someone holds the lock."); 4447 // Set the global evac-failure closure to the current thread's. 4448 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4449 set_evac_failure_closure(cl); 4450 // Now do the common part. 4451 handle_evacuation_failure_common(old, m); 4452 // Reset to NULL. 4453 set_evac_failure_closure(NULL); 4454 } else { 4455 // The lock is already held, and this is recursive. 4456 assert(_drain_in_progress, "This should only be the recursive case."); 4457 handle_evacuation_failure_common(old, m); 4458 } 4459 return old; 4460 } else { 4461 // Forward-to-self failed. Either someone else managed to allocate 4462 // space for this object (old != forward_ptr) or they beat us in 4463 // self-forwarding it (old == forward_ptr). 4464 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4465 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4466 "should not be in the CSet", 4467 (HeapWord*) old, (HeapWord*) forward_ptr)); 4468 return forward_ptr; 4469 } 4470 } 4471 4472 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4473 preserve_mark_if_necessary(old, m); 4474 4475 HeapRegion* r = heap_region_containing(old); 4476 if (!r->evacuation_failed()) { 4477 r->set_evacuation_failed(true); 4478 _hr_printer.evac_failure(r); 4479 } 4480 4481 push_on_evac_failure_scan_stack(old); 4482 4483 if (!_drain_in_progress) { 4484 // prevent recursion in copy_to_survivor_space() 4485 _drain_in_progress = true; 4486 drain_evac_failure_scan_stack(); 4487 _drain_in_progress = false; 4488 } 4489 } 4490 4491 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4492 assert(evacuation_failed(), "Oversaving!"); 4493 // We want to call the "for_promotion_failure" version only in the 4494 // case of a promotion failure. 4495 if (m->must_be_preserved_for_promotion_failure(obj)) { 4496 _objs_with_preserved_marks.push(obj); 4497 _preserved_marks_of_objs.push(m); 4498 } 4499 } 4500 4501 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4502 size_t word_size) { 4503 if (purpose == GCAllocForSurvived) { 4504 HeapWord* result = survivor_attempt_allocation(word_size); 4505 if (result != NULL) { 4506 return result; 4507 } else { 4508 // Let's try to allocate in the old gen in case we can fit the 4509 // object there. 4510 return old_attempt_allocation(word_size); 4511 } 4512 } else { 4513 assert(purpose == GCAllocForTenured, "sanity"); 4514 HeapWord* result = old_attempt_allocation(word_size); 4515 if (result != NULL) { 4516 return result; 4517 } else { 4518 // Let's try to allocate in the survivors in case we can fit the 4519 // object there. 4520 return survivor_attempt_allocation(word_size); 4521 } 4522 } 4523 4524 ShouldNotReachHere(); 4525 // Trying to keep some compilers happy. 4526 return NULL; 4527 } 4528 4529 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4530 ParGCAllocBuffer(gclab_word_size), _retired(false) { } 4531 4532 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num) 4533 : _g1h(g1h), 4534 _refs(g1h->task_queue(queue_num)), 4535 _dcq(&g1h->dirty_card_queue_set()), 4536 _ct_bs(g1h->g1_barrier_set()), 4537 _g1_rem(g1h->g1_rem_set()), 4538 _hash_seed(17), _queue_num(queue_num), 4539 _term_attempts(0), 4540 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4541 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4542 _age_table(false), 4543 _strong_roots_time(0), _term_time(0), 4544 _alloc_buffer_waste(0), _undo_waste(0) { 4545 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4546 // we "sacrifice" entry 0 to keep track of surviving bytes for 4547 // non-young regions (where the age is -1) 4548 // We also add a few elements at the beginning and at the end in 4549 // an attempt to eliminate cache contention 4550 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4551 uint array_length = PADDING_ELEM_NUM + 4552 real_length + 4553 PADDING_ELEM_NUM; 4554 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4555 if (_surviving_young_words_base == NULL) 4556 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 4557 "Not enough space for young surv histo."); 4558 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4559 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4560 4561 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4562 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4563 4564 _start = os::elapsedTime(); 4565 } 4566 4567 void 4568 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4569 { 4570 st->print_raw_cr("GC Termination Stats"); 4571 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4572 " ------waste (KiB)------"); 4573 st->print_raw_cr("thr ms ms % ms % attempts" 4574 " total alloc undo"); 4575 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4576 " ------- ------- -------"); 4577 } 4578 4579 void 4580 G1ParScanThreadState::print_termination_stats(int i, 4581 outputStream* const st) const 4582 { 4583 const double elapsed_ms = elapsed_time() * 1000.0; 4584 const double s_roots_ms = strong_roots_time() * 1000.0; 4585 const double term_ms = term_time() * 1000.0; 4586 st->print_cr("%3d %9.2f %9.2f %6.2f " 4587 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4588 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4589 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4590 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4591 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4592 alloc_buffer_waste() * HeapWordSize / K, 4593 undo_waste() * HeapWordSize / K); 4594 } 4595 4596 #ifdef ASSERT 4597 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4598 assert(ref != NULL, "invariant"); 4599 assert(UseCompressedOops, "sanity"); 4600 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4601 oop p = oopDesc::load_decode_heap_oop(ref); 4602 assert(_g1h->is_in_g1_reserved(p), 4603 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4604 return true; 4605 } 4606 4607 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4608 assert(ref != NULL, "invariant"); 4609 if (has_partial_array_mask(ref)) { 4610 // Must be in the collection set--it's already been copied. 4611 oop p = clear_partial_array_mask(ref); 4612 assert(_g1h->obj_in_cs(p), 4613 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4614 } else { 4615 oop p = oopDesc::load_decode_heap_oop(ref); 4616 assert(_g1h->is_in_g1_reserved(p), 4617 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4618 } 4619 return true; 4620 } 4621 4622 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4623 if (ref.is_narrow()) { 4624 return verify_ref((narrowOop*) ref); 4625 } else { 4626 return verify_ref((oop*) ref); 4627 } 4628 } 4629 #endif // ASSERT 4630 4631 void G1ParScanThreadState::trim_queue() { 4632 assert(_evac_cl != NULL, "not set"); 4633 assert(_evac_failure_cl != NULL, "not set"); 4634 assert(_partial_scan_cl != NULL, "not set"); 4635 4636 StarTask ref; 4637 do { 4638 // Drain the overflow stack first, so other threads can steal. 4639 while (refs()->pop_overflow(ref)) { 4640 deal_with_reference(ref); 4641 } 4642 4643 while (refs()->pop_local(ref)) { 4644 deal_with_reference(ref); 4645 } 4646 } while (!refs()->is_empty()); 4647 } 4648 4649 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4650 G1ParScanThreadState* par_scan_state) : 4651 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()), 4652 _par_scan_state(par_scan_state), 4653 _worker_id(par_scan_state->queue_num()), 4654 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()), 4655 _mark_in_progress(_g1->mark_in_progress()) { } 4656 4657 template <G1Barrier barrier, bool do_mark_object> 4658 void G1ParCopyClosure<barrier, do_mark_object>::mark_object(oop obj) { 4659 #ifdef ASSERT 4660 HeapRegion* hr = _g1->heap_region_containing(obj); 4661 assert(hr != NULL, "sanity"); 4662 assert(!hr->in_collection_set(), "should not mark objects in the CSet"); 4663 #endif // ASSERT 4664 4665 // We know that the object is not moving so it's safe to read its size. 4666 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4667 } 4668 4669 template <G1Barrier barrier, bool do_mark_object> 4670 void G1ParCopyClosure<barrier, do_mark_object> 4671 ::mark_forwarded_object(oop from_obj, oop to_obj) { 4672 #ifdef ASSERT 4673 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4674 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4675 assert(from_obj != to_obj, "should not be self-forwarded"); 4676 4677 HeapRegion* from_hr = _g1->heap_region_containing(from_obj); 4678 assert(from_hr != NULL, "sanity"); 4679 assert(from_hr->in_collection_set(), "from obj should be in the CSet"); 4680 4681 HeapRegion* to_hr = _g1->heap_region_containing(to_obj); 4682 assert(to_hr != NULL, "sanity"); 4683 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet"); 4684 #endif // ASSERT 4685 4686 // The object might be in the process of being copied by another 4687 // worker so we cannot trust that its to-space image is 4688 // well-formed. So we have to read its size from its from-space 4689 // image which we know should not be changing. 4690 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4691 } 4692 4693 template <G1Barrier barrier, bool do_mark_object> 4694 oop G1ParCopyClosure<barrier, do_mark_object> 4695 ::copy_to_survivor_space(oop old) { 4696 size_t word_sz = old->size(); 4697 HeapRegion* from_region = _g1->heap_region_containing_raw(old); 4698 // +1 to make the -1 indexes valid... 4699 int young_index = from_region->young_index_in_cset()+1; 4700 assert( (from_region->is_young() && young_index > 0) || 4701 (!from_region->is_young() && young_index == 0), "invariant" ); 4702 G1CollectorPolicy* g1p = _g1->g1_policy(); 4703 markOop m = old->mark(); 4704 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4705 : m->age(); 4706 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4707 word_sz); 4708 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz); 4709 #ifndef PRODUCT 4710 // Should this evacuation fail? 4711 if (_g1->evacuation_should_fail()) { 4712 if (obj_ptr != NULL) { 4713 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4714 obj_ptr = NULL; 4715 } 4716 } 4717 #endif // !PRODUCT 4718 4719 if (obj_ptr == NULL) { 4720 // This will either forward-to-self, or detect that someone else has 4721 // installed a forwarding pointer. 4722 return _g1->handle_evacuation_failure_par(_par_scan_state, old); 4723 } 4724 4725 oop obj = oop(obj_ptr); 4726 4727 // We're going to allocate linearly, so might as well prefetch ahead. 4728 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4729 4730 oop forward_ptr = old->forward_to_atomic(obj); 4731 if (forward_ptr == NULL) { 4732 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4733 if (g1p->track_object_age(alloc_purpose)) { 4734 // We could simply do obj->incr_age(). However, this causes a 4735 // performance issue. obj->incr_age() will first check whether 4736 // the object has a displaced mark by checking its mark word; 4737 // getting the mark word from the new location of the object 4738 // stalls. So, given that we already have the mark word and we 4739 // are about to install it anyway, it's better to increase the 4740 // age on the mark word, when the object does not have a 4741 // displaced mark word. We're not expecting many objects to have 4742 // a displaced marked word, so that case is not optimized 4743 // further (it could be...) and we simply call obj->incr_age(). 4744 4745 if (m->has_displaced_mark_helper()) { 4746 // in this case, we have to install the mark word first, 4747 // otherwise obj looks to be forwarded (the old mark word, 4748 // which contains the forward pointer, was copied) 4749 obj->set_mark(m); 4750 obj->incr_age(); 4751 } else { 4752 m = m->incr_age(); 4753 obj->set_mark(m); 4754 } 4755 _par_scan_state->age_table()->add(obj, word_sz); 4756 } else { 4757 obj->set_mark(m); 4758 } 4759 4760 size_t* surv_young_words = _par_scan_state->surviving_young_words(); 4761 surv_young_words[young_index] += word_sz; 4762 4763 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4764 // We keep track of the next start index in the length field of 4765 // the to-space object. The actual length can be found in the 4766 // length field of the from-space object. 4767 arrayOop(obj)->set_length(0); 4768 oop* old_p = set_partial_array_mask(old); 4769 _par_scan_state->push_on_queue(old_p); 4770 } else { 4771 // No point in using the slower heap_region_containing() method, 4772 // given that we know obj is in the heap. 4773 _scanner.set_region(_g1->heap_region_containing_raw(obj)); 4774 obj->oop_iterate_backwards(&_scanner); 4775 } 4776 } else { 4777 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4778 obj = forward_ptr; 4779 } 4780 return obj; 4781 } 4782 4783 template <class T> 4784 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4785 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4786 _scanned_klass->record_modified_oops(); 4787 } 4788 } 4789 4790 template <G1Barrier barrier, bool do_mark_object> 4791 template <class T> 4792 void G1ParCopyClosure<barrier, do_mark_object> 4793 ::do_oop_work(T* p) { 4794 oop obj = oopDesc::load_decode_heap_oop(p); 4795 4796 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4797 4798 // here the null check is implicit in the cset_fast_test() test 4799 if (_g1->in_cset_fast_test(obj)) { 4800 oop forwardee; 4801 if (obj->is_forwarded()) { 4802 forwardee = obj->forwardee(); 4803 } else { 4804 forwardee = copy_to_survivor_space(obj); 4805 } 4806 assert(forwardee != NULL, "forwardee should not be NULL"); 4807 oopDesc::encode_store_heap_oop(p, forwardee); 4808 if (do_mark_object && forwardee != obj) { 4809 // If the object is self-forwarded we don't need to explicitly 4810 // mark it, the evacuation failure protocol will do so. 4811 mark_forwarded_object(obj, forwardee); 4812 } 4813 4814 if (barrier == G1BarrierKlass) { 4815 do_klass_barrier(p, forwardee); 4816 } 4817 } else { 4818 // The object is not in collection set. If we're a root scanning 4819 // closure during an initial mark pause (i.e. do_mark_object will 4820 // be true) then attempt to mark the object. 4821 if (do_mark_object && _g1->is_in_g1_reserved(obj)) { 4822 mark_object(obj); 4823 } 4824 } 4825 4826 if (barrier == G1BarrierEvac && obj != NULL) { 4827 _par_scan_state->update_rs(_from, p, _worker_id); 4828 } 4829 } 4830 4831 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p); 4832 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4833 4834 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) { 4835 assert(has_partial_array_mask(p), "invariant"); 4836 oop from_obj = clear_partial_array_mask(p); 4837 4838 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap."); 4839 assert(from_obj->is_objArray(), "must be obj array"); 4840 objArrayOop from_obj_array = objArrayOop(from_obj); 4841 // The from-space object contains the real length. 4842 int length = from_obj_array->length(); 4843 4844 assert(from_obj->is_forwarded(), "must be forwarded"); 4845 oop to_obj = from_obj->forwardee(); 4846 assert(from_obj != to_obj, "should not be chunking self-forwarded objects"); 4847 objArrayOop to_obj_array = objArrayOop(to_obj); 4848 // We keep track of the next start index in the length field of the 4849 // to-space object. 4850 int next_index = to_obj_array->length(); 4851 assert(0 <= next_index && next_index < length, 4852 err_msg("invariant, next index: %d, length: %d", next_index, length)); 4853 4854 int start = next_index; 4855 int end = length; 4856 int remainder = end - start; 4857 // We'll try not to push a range that's smaller than ParGCArrayScanChunk. 4858 if (remainder > 2 * ParGCArrayScanChunk) { 4859 end = start + ParGCArrayScanChunk; 4860 to_obj_array->set_length(end); 4861 // Push the remainder before we process the range in case another 4862 // worker has run out of things to do and can steal it. 4863 oop* from_obj_p = set_partial_array_mask(from_obj); 4864 _par_scan_state->push_on_queue(from_obj_p); 4865 } else { 4866 assert(length == end, "sanity"); 4867 // We'll process the final range for this object. Restore the length 4868 // so that the heap remains parsable in case of evacuation failure. 4869 to_obj_array->set_length(end); 4870 } 4871 _scanner.set_region(_g1->heap_region_containing_raw(to_obj)); 4872 // Process indexes [start,end). It will also process the header 4873 // along with the first chunk (i.e., the chunk with start == 0). 4874 // Note that at this point the length field of to_obj_array is not 4875 // correct given that we are using it to keep track of the next 4876 // start index. oop_iterate_range() (thankfully!) ignores the length 4877 // field and only relies on the start / end parameters. It does 4878 // however return the size of the object which will be incorrect. So 4879 // we have to ignore it even if we wanted to use it. 4880 to_obj_array->oop_iterate_range(&_scanner, start, end); 4881 } 4882 4883 class G1ParEvacuateFollowersClosure : public VoidClosure { 4884 protected: 4885 G1CollectedHeap* _g1h; 4886 G1ParScanThreadState* _par_scan_state; 4887 RefToScanQueueSet* _queues; 4888 ParallelTaskTerminator* _terminator; 4889 4890 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4891 RefToScanQueueSet* queues() { return _queues; } 4892 ParallelTaskTerminator* terminator() { return _terminator; } 4893 4894 public: 4895 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4896 G1ParScanThreadState* par_scan_state, 4897 RefToScanQueueSet* queues, 4898 ParallelTaskTerminator* terminator) 4899 : _g1h(g1h), _par_scan_state(par_scan_state), 4900 _queues(queues), _terminator(terminator) {} 4901 4902 void do_void(); 4903 4904 private: 4905 inline bool offer_termination(); 4906 }; 4907 4908 bool G1ParEvacuateFollowersClosure::offer_termination() { 4909 G1ParScanThreadState* const pss = par_scan_state(); 4910 pss->start_term_time(); 4911 const bool res = terminator()->offer_termination(); 4912 pss->end_term_time(); 4913 return res; 4914 } 4915 4916 void G1ParEvacuateFollowersClosure::do_void() { 4917 StarTask stolen_task; 4918 G1ParScanThreadState* const pss = par_scan_state(); 4919 pss->trim_queue(); 4920 4921 do { 4922 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4923 assert(pss->verify_task(stolen_task), "sanity"); 4924 if (stolen_task.is_narrow()) { 4925 pss->deal_with_reference((narrowOop*) stolen_task); 4926 } else { 4927 pss->deal_with_reference((oop*) stolen_task); 4928 } 4929 4930 // We've just processed a reference and we might have made 4931 // available new entries on the queues. So we have to make sure 4932 // we drain the queues as necessary. 4933 pss->trim_queue(); 4934 } 4935 } while (!offer_termination()); 4936 4937 pss->retire_alloc_buffers(); 4938 } 4939 4940 class G1KlassScanClosure : public KlassClosure { 4941 G1ParCopyHelper* _closure; 4942 bool _process_only_dirty; 4943 int _count; 4944 public: 4945 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4946 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4947 void do_klass(Klass* klass) { 4948 // If the klass has not been dirtied we know that there's 4949 // no references into the young gen and we can skip it. 4950 if (!_process_only_dirty || klass->has_modified_oops()) { 4951 // Clean the klass since we're going to scavenge all the metadata. 4952 klass->clear_modified_oops(); 4953 4954 // Tell the closure that this klass is the Klass to scavenge 4955 // and is the one to dirty if oops are left pointing into the young gen. 4956 _closure->set_scanned_klass(klass); 4957 4958 klass->oops_do(_closure); 4959 4960 _closure->set_scanned_klass(NULL); 4961 } 4962 _count++; 4963 } 4964 }; 4965 4966 class G1ParTask : public AbstractGangTask { 4967 protected: 4968 G1CollectedHeap* _g1h; 4969 RefToScanQueueSet *_queues; 4970 ParallelTaskTerminator _terminator; 4971 uint _n_workers; 4972 4973 Mutex _stats_lock; 4974 Mutex* stats_lock() { return &_stats_lock; } 4975 4976 size_t getNCards() { 4977 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4978 / G1BlockOffsetSharedArray::N_bytes; 4979 } 4980 4981 public: 4982 G1ParTask(G1CollectedHeap* g1h, 4983 RefToScanQueueSet *task_queues) 4984 : AbstractGangTask("G1 collection"), 4985 _g1h(g1h), 4986 _queues(task_queues), 4987 _terminator(0, _queues), 4988 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4989 {} 4990 4991 RefToScanQueueSet* queues() { return _queues; } 4992 4993 RefToScanQueue *work_queue(int i) { 4994 return queues()->queue(i); 4995 } 4996 4997 ParallelTaskTerminator* terminator() { return &_terminator; } 4998 4999 virtual void set_for_termination(int active_workers) { 5000 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 5001 // in the young space (_par_seq_tasks) in the G1 heap 5002 // for SequentialSubTasksDone. 5003 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 5004 // both of which need setting by set_n_termination(). 5005 _g1h->SharedHeap::set_n_termination(active_workers); 5006 _g1h->set_n_termination(active_workers); 5007 terminator()->reset_for_reuse(active_workers); 5008 _n_workers = active_workers; 5009 } 5010 5011 void work(uint worker_id) { 5012 if (worker_id >= _n_workers) return; // no work needed this round 5013 5014 double start_time_ms = os::elapsedTime() * 1000.0; 5015 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 5016 5017 { 5018 ResourceMark rm; 5019 HandleMark hm; 5020 5021 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 5022 5023 G1ParScanThreadState pss(_g1h, worker_id); 5024 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp); 5025 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 5026 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp); 5027 5028 pss.set_evac_closure(&scan_evac_cl); 5029 pss.set_evac_failure_closure(&evac_failure_cl); 5030 pss.set_partial_scan_closure(&partial_scan_cl); 5031 5032 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 5033 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 5034 5035 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 5036 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 5037 5038 bool only_young = _g1h->g1_policy()->gcs_are_young(); 5039 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 5040 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 5041 5042 OopClosure* scan_root_cl = &only_scan_root_cl; 5043 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 5044 5045 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5046 // We also need to mark copied objects. 5047 scan_root_cl = &scan_mark_root_cl; 5048 scan_klasses_cl = &scan_mark_klasses_cl_s; 5049 } 5050 5051 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 5052 5053 // Don't scan the scavengable methods in the code cache as part 5054 // of strong root scanning. The code roots that point into a 5055 // region in the collection set are scanned when we scan the 5056 // region's RSet. 5057 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings; 5058 5059 pss.start_strong_roots(); 5060 _g1h->g1_process_strong_roots(/* is scavenging */ true, 5061 SharedHeap::ScanningOption(so), 5062 scan_root_cl, 5063 &push_heap_rs_cl, 5064 scan_klasses_cl, 5065 worker_id); 5066 pss.end_strong_roots(); 5067 5068 { 5069 double start = os::elapsedTime(); 5070 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 5071 evac.do_void(); 5072 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 5073 double term_ms = pss.term_time()*1000.0; 5074 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 5075 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 5076 } 5077 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 5078 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 5079 5080 if (ParallelGCVerbose) { 5081 MutexLocker x(stats_lock()); 5082 pss.print_termination_stats(worker_id); 5083 } 5084 5085 assert(pss.refs()->is_empty(), "should be empty"); 5086 5087 // Close the inner scope so that the ResourceMark and HandleMark 5088 // destructors are executed here and are included as part of the 5089 // "GC Worker Time". 5090 } 5091 5092 double end_time_ms = os::elapsedTime() * 1000.0; 5093 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 5094 } 5095 }; 5096 5097 // *** Common G1 Evacuation Stuff 5098 5099 // This method is run in a GC worker. 5100 5101 void 5102 G1CollectedHeap:: 5103 g1_process_strong_roots(bool is_scavenging, 5104 ScanningOption so, 5105 OopClosure* scan_non_heap_roots, 5106 OopsInHeapRegionClosure* scan_rs, 5107 G1KlassScanClosure* scan_klasses, 5108 int worker_i) { 5109 5110 // First scan the strong roots 5111 double ext_roots_start = os::elapsedTime(); 5112 double closure_app_time_sec = 0.0; 5113 5114 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5115 5116 assert(so & SO_AllCodeCache || scan_rs != NULL, "must scan code roots somehow"); 5117 // Walk the code cache/strong code roots w/o buffering, because StarTask 5118 // cannot handle unaligned oop locations. 5119 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */); 5120 5121 process_strong_roots(false, // no scoping; this is parallel code 5122 so, 5123 &buf_scan_non_heap_roots, 5124 &eager_scan_code_roots, 5125 scan_klasses 5126 ); 5127 5128 // Now the CM ref_processor roots. 5129 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5130 // We need to treat the discovered reference lists of the 5131 // concurrent mark ref processor as roots and keep entries 5132 // (which are added by the marking threads) on them live 5133 // until they can be processed at the end of marking. 5134 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5135 } 5136 5137 // Finish up any enqueued closure apps (attributed as object copy time). 5138 buf_scan_non_heap_roots.done(); 5139 5140 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 5141 5142 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5143 5144 double ext_root_time_ms = 5145 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5146 5147 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5148 5149 // During conc marking we have to filter the per-thread SATB buffers 5150 // to make sure we remove any oops into the CSet (which will show up 5151 // as implicitly live). 5152 double satb_filtering_ms = 0.0; 5153 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5154 if (mark_in_progress()) { 5155 double satb_filter_start = os::elapsedTime(); 5156 5157 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5158 5159 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5160 } 5161 } 5162 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5163 5164 // If this is an initial mark pause, and we're not scanning 5165 // the entire code cache, we need to mark the oops in the 5166 // strong code root lists for the regions that are not in 5167 // the collection set. 5168 // Note all threads participate in this set of root tasks. 5169 double mark_strong_code_roots_ms = 0.0; 5170 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) { 5171 double mark_strong_roots_start = os::elapsedTime(); 5172 mark_strong_code_roots(worker_i); 5173 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0; 5174 } 5175 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms); 5176 5177 // Now scan the complement of the collection set. 5178 if (scan_rs != NULL) { 5179 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i); 5180 } 5181 _process_strong_tasks->all_tasks_completed(); 5182 } 5183 5184 void 5185 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) { 5186 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false); 5187 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs); 5188 } 5189 5190 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 5191 private: 5192 BoolObjectClosure* _is_alive; 5193 int _initial_string_table_size; 5194 int _initial_symbol_table_size; 5195 5196 bool _process_strings; 5197 int _strings_processed; 5198 int _strings_removed; 5199 5200 bool _process_symbols; 5201 int _symbols_processed; 5202 int _symbols_removed; 5203 5204 bool _do_in_parallel; 5205 public: 5206 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 5207 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive), 5208 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 5209 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 5210 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 5211 5212 _initial_string_table_size = StringTable::the_table()->table_size(); 5213 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 5214 if (process_strings) { 5215 StringTable::clear_parallel_claimed_index(); 5216 } 5217 if (process_symbols) { 5218 SymbolTable::clear_parallel_claimed_index(); 5219 } 5220 } 5221 5222 ~G1StringSymbolTableUnlinkTask() { 5223 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 5224 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT, 5225 StringTable::parallel_claimed_index(), _initial_string_table_size)); 5226 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 5227 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT, 5228 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 5229 } 5230 5231 void work(uint worker_id) { 5232 if (_do_in_parallel) { 5233 int strings_processed = 0; 5234 int strings_removed = 0; 5235 int symbols_processed = 0; 5236 int symbols_removed = 0; 5237 if (_process_strings) { 5238 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5239 Atomic::add(strings_processed, &_strings_processed); 5240 Atomic::add(strings_removed, &_strings_removed); 5241 } 5242 if (_process_symbols) { 5243 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5244 Atomic::add(symbols_processed, &_symbols_processed); 5245 Atomic::add(symbols_removed, &_symbols_removed); 5246 } 5247 } else { 5248 if (_process_strings) { 5249 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5250 } 5251 if (_process_symbols) { 5252 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5253 } 5254 } 5255 } 5256 5257 size_t strings_processed() const { return (size_t)_strings_processed; } 5258 size_t strings_removed() const { return (size_t)_strings_removed; } 5259 5260 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5261 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5262 }; 5263 5264 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5265 bool process_strings, bool process_symbols) { 5266 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5267 _g1h->workers()->active_workers() : 1); 5268 5269 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5270 if (G1CollectedHeap::use_parallel_gc_threads()) { 5271 set_par_threads(n_workers); 5272 workers()->run_task(&g1_unlink_task); 5273 set_par_threads(0); 5274 } else { 5275 g1_unlink_task.work(0); 5276 } 5277 if (G1TraceStringSymbolTableScrubbing) { 5278 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5279 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5280 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5281 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(), 5282 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed()); 5283 } 5284 } 5285 5286 // Weak Reference Processing support 5287 5288 // An always "is_alive" closure that is used to preserve referents. 5289 // If the object is non-null then it's alive. Used in the preservation 5290 // of referent objects that are pointed to by reference objects 5291 // discovered by the CM ref processor. 5292 class G1AlwaysAliveClosure: public BoolObjectClosure { 5293 G1CollectedHeap* _g1; 5294 public: 5295 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5296 bool do_object_b(oop p) { 5297 if (p != NULL) { 5298 return true; 5299 } 5300 return false; 5301 } 5302 }; 5303 5304 bool G1STWIsAliveClosure::do_object_b(oop p) { 5305 // An object is reachable if it is outside the collection set, 5306 // or is inside and copied. 5307 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5308 } 5309 5310 // Non Copying Keep Alive closure 5311 class G1KeepAliveClosure: public OopClosure { 5312 G1CollectedHeap* _g1; 5313 public: 5314 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5315 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5316 void do_oop( oop* p) { 5317 oop obj = *p; 5318 5319 if (_g1->obj_in_cs(obj)) { 5320 assert( obj->is_forwarded(), "invariant" ); 5321 *p = obj->forwardee(); 5322 } 5323 } 5324 }; 5325 5326 // Copying Keep Alive closure - can be called from both 5327 // serial and parallel code as long as different worker 5328 // threads utilize different G1ParScanThreadState instances 5329 // and different queues. 5330 5331 class G1CopyingKeepAliveClosure: public OopClosure { 5332 G1CollectedHeap* _g1h; 5333 OopClosure* _copy_non_heap_obj_cl; 5334 OopsInHeapRegionClosure* _copy_metadata_obj_cl; 5335 G1ParScanThreadState* _par_scan_state; 5336 5337 public: 5338 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5339 OopClosure* non_heap_obj_cl, 5340 OopsInHeapRegionClosure* metadata_obj_cl, 5341 G1ParScanThreadState* pss): 5342 _g1h(g1h), 5343 _copy_non_heap_obj_cl(non_heap_obj_cl), 5344 _copy_metadata_obj_cl(metadata_obj_cl), 5345 _par_scan_state(pss) 5346 {} 5347 5348 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5349 virtual void do_oop( oop* p) { do_oop_work(p); } 5350 5351 template <class T> void do_oop_work(T* p) { 5352 oop obj = oopDesc::load_decode_heap_oop(p); 5353 5354 if (_g1h->obj_in_cs(obj)) { 5355 // If the referent object has been forwarded (either copied 5356 // to a new location or to itself in the event of an 5357 // evacuation failure) then we need to update the reference 5358 // field and, if both reference and referent are in the G1 5359 // heap, update the RSet for the referent. 5360 // 5361 // If the referent has not been forwarded then we have to keep 5362 // it alive by policy. Therefore we have copy the referent. 5363 // 5364 // If the reference field is in the G1 heap then we can push 5365 // on the PSS queue. When the queue is drained (after each 5366 // phase of reference processing) the object and it's followers 5367 // will be copied, the reference field set to point to the 5368 // new location, and the RSet updated. Otherwise we need to 5369 // use the the non-heap or metadata closures directly to copy 5370 // the referent object and update the pointer, while avoiding 5371 // updating the RSet. 5372 5373 if (_g1h->is_in_g1_reserved(p)) { 5374 _par_scan_state->push_on_queue(p); 5375 } else { 5376 assert(!ClassLoaderDataGraph::contains((address)p), 5377 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) " 5378 PTR_FORMAT, p)); 5379 _copy_non_heap_obj_cl->do_oop(p); 5380 } 5381 } 5382 } 5383 }; 5384 5385 // Serial drain queue closure. Called as the 'complete_gc' 5386 // closure for each discovered list in some of the 5387 // reference processing phases. 5388 5389 class G1STWDrainQueueClosure: public VoidClosure { 5390 protected: 5391 G1CollectedHeap* _g1h; 5392 G1ParScanThreadState* _par_scan_state; 5393 5394 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5395 5396 public: 5397 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5398 _g1h(g1h), 5399 _par_scan_state(pss) 5400 { } 5401 5402 void do_void() { 5403 G1ParScanThreadState* const pss = par_scan_state(); 5404 pss->trim_queue(); 5405 } 5406 }; 5407 5408 // Parallel Reference Processing closures 5409 5410 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5411 // processing during G1 evacuation pauses. 5412 5413 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5414 private: 5415 G1CollectedHeap* _g1h; 5416 RefToScanQueueSet* _queues; 5417 FlexibleWorkGang* _workers; 5418 int _active_workers; 5419 5420 public: 5421 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5422 FlexibleWorkGang* workers, 5423 RefToScanQueueSet *task_queues, 5424 int n_workers) : 5425 _g1h(g1h), 5426 _queues(task_queues), 5427 _workers(workers), 5428 _active_workers(n_workers) 5429 { 5430 assert(n_workers > 0, "shouldn't call this otherwise"); 5431 } 5432 5433 // Executes the given task using concurrent marking worker threads. 5434 virtual void execute(ProcessTask& task); 5435 virtual void execute(EnqueueTask& task); 5436 }; 5437 5438 // Gang task for possibly parallel reference processing 5439 5440 class G1STWRefProcTaskProxy: public AbstractGangTask { 5441 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5442 ProcessTask& _proc_task; 5443 G1CollectedHeap* _g1h; 5444 RefToScanQueueSet *_task_queues; 5445 ParallelTaskTerminator* _terminator; 5446 5447 public: 5448 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5449 G1CollectedHeap* g1h, 5450 RefToScanQueueSet *task_queues, 5451 ParallelTaskTerminator* terminator) : 5452 AbstractGangTask("Process reference objects in parallel"), 5453 _proc_task(proc_task), 5454 _g1h(g1h), 5455 _task_queues(task_queues), 5456 _terminator(terminator) 5457 {} 5458 5459 virtual void work(uint worker_id) { 5460 // The reference processing task executed by a single worker. 5461 ResourceMark rm; 5462 HandleMark hm; 5463 5464 G1STWIsAliveClosure is_alive(_g1h); 5465 5466 G1ParScanThreadState pss(_g1h, worker_id); 5467 5468 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5469 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5470 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5471 5472 pss.set_evac_closure(&scan_evac_cl); 5473 pss.set_evac_failure_closure(&evac_failure_cl); 5474 pss.set_partial_scan_closure(&partial_scan_cl); 5475 5476 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5477 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5478 5479 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5480 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5481 5482 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5483 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5484 5485 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5486 // We also need to mark copied objects. 5487 copy_non_heap_cl = ©_mark_non_heap_cl; 5488 copy_metadata_cl = ©_mark_metadata_cl; 5489 } 5490 5491 // Keep alive closure. 5492 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5493 5494 // Complete GC closure 5495 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5496 5497 // Call the reference processing task's work routine. 5498 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5499 5500 // Note we cannot assert that the refs array is empty here as not all 5501 // of the processing tasks (specifically phase2 - pp2_work) execute 5502 // the complete_gc closure (which ordinarily would drain the queue) so 5503 // the queue may not be empty. 5504 } 5505 }; 5506 5507 // Driver routine for parallel reference processing. 5508 // Creates an instance of the ref processing gang 5509 // task and has the worker threads execute it. 5510 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5511 assert(_workers != NULL, "Need parallel worker threads."); 5512 5513 ParallelTaskTerminator terminator(_active_workers, _queues); 5514 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5515 5516 _g1h->set_par_threads(_active_workers); 5517 _workers->run_task(&proc_task_proxy); 5518 _g1h->set_par_threads(0); 5519 } 5520 5521 // Gang task for parallel reference enqueueing. 5522 5523 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5524 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5525 EnqueueTask& _enq_task; 5526 5527 public: 5528 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5529 AbstractGangTask("Enqueue reference objects in parallel"), 5530 _enq_task(enq_task) 5531 { } 5532 5533 virtual void work(uint worker_id) { 5534 _enq_task.work(worker_id); 5535 } 5536 }; 5537 5538 // Driver routine for parallel reference enqueueing. 5539 // Creates an instance of the ref enqueueing gang 5540 // task and has the worker threads execute it. 5541 5542 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5543 assert(_workers != NULL, "Need parallel worker threads."); 5544 5545 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5546 5547 _g1h->set_par_threads(_active_workers); 5548 _workers->run_task(&enq_task_proxy); 5549 _g1h->set_par_threads(0); 5550 } 5551 5552 // End of weak reference support closures 5553 5554 // Abstract task used to preserve (i.e. copy) any referent objects 5555 // that are in the collection set and are pointed to by reference 5556 // objects discovered by the CM ref processor. 5557 5558 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5559 protected: 5560 G1CollectedHeap* _g1h; 5561 RefToScanQueueSet *_queues; 5562 ParallelTaskTerminator _terminator; 5563 uint _n_workers; 5564 5565 public: 5566 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5567 AbstractGangTask("ParPreserveCMReferents"), 5568 _g1h(g1h), 5569 _queues(task_queues), 5570 _terminator(workers, _queues), 5571 _n_workers(workers) 5572 { } 5573 5574 void work(uint worker_id) { 5575 ResourceMark rm; 5576 HandleMark hm; 5577 5578 G1ParScanThreadState pss(_g1h, worker_id); 5579 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5580 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5581 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5582 5583 pss.set_evac_closure(&scan_evac_cl); 5584 pss.set_evac_failure_closure(&evac_failure_cl); 5585 pss.set_partial_scan_closure(&partial_scan_cl); 5586 5587 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5588 5589 5590 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5591 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5592 5593 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5594 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5595 5596 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5597 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5598 5599 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5600 // We also need to mark copied objects. 5601 copy_non_heap_cl = ©_mark_non_heap_cl; 5602 copy_metadata_cl = ©_mark_metadata_cl; 5603 } 5604 5605 // Is alive closure 5606 G1AlwaysAliveClosure always_alive(_g1h); 5607 5608 // Copying keep alive closure. Applied to referent objects that need 5609 // to be copied. 5610 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5611 5612 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5613 5614 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5615 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5616 5617 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5618 // So this must be true - but assert just in case someone decides to 5619 // change the worker ids. 5620 assert(0 <= worker_id && worker_id < limit, "sanity"); 5621 assert(!rp->discovery_is_atomic(), "check this code"); 5622 5623 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5624 for (uint idx = worker_id; idx < limit; idx += stride) { 5625 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5626 5627 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5628 while (iter.has_next()) { 5629 // Since discovery is not atomic for the CM ref processor, we 5630 // can see some null referent objects. 5631 iter.load_ptrs(DEBUG_ONLY(true)); 5632 oop ref = iter.obj(); 5633 5634 // This will filter nulls. 5635 if (iter.is_referent_alive()) { 5636 iter.make_referent_alive(); 5637 } 5638 iter.move_to_next(); 5639 } 5640 } 5641 5642 // Drain the queue - which may cause stealing 5643 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5644 drain_queue.do_void(); 5645 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5646 assert(pss.refs()->is_empty(), "should be"); 5647 } 5648 }; 5649 5650 // Weak Reference processing during an evacuation pause (part 1). 5651 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5652 double ref_proc_start = os::elapsedTime(); 5653 5654 ReferenceProcessor* rp = _ref_processor_stw; 5655 assert(rp->discovery_enabled(), "should have been enabled"); 5656 5657 // Any reference objects, in the collection set, that were 'discovered' 5658 // by the CM ref processor should have already been copied (either by 5659 // applying the external root copy closure to the discovered lists, or 5660 // by following an RSet entry). 5661 // 5662 // But some of the referents, that are in the collection set, that these 5663 // reference objects point to may not have been copied: the STW ref 5664 // processor would have seen that the reference object had already 5665 // been 'discovered' and would have skipped discovering the reference, 5666 // but would not have treated the reference object as a regular oop. 5667 // As a result the copy closure would not have been applied to the 5668 // referent object. 5669 // 5670 // We need to explicitly copy these referent objects - the references 5671 // will be processed at the end of remarking. 5672 // 5673 // We also need to do this copying before we process the reference 5674 // objects discovered by the STW ref processor in case one of these 5675 // referents points to another object which is also referenced by an 5676 // object discovered by the STW ref processor. 5677 5678 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5679 no_of_gc_workers == workers()->active_workers(), 5680 "Need to reset active GC workers"); 5681 5682 set_par_threads(no_of_gc_workers); 5683 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5684 no_of_gc_workers, 5685 _task_queues); 5686 5687 if (G1CollectedHeap::use_parallel_gc_threads()) { 5688 workers()->run_task(&keep_cm_referents); 5689 } else { 5690 keep_cm_referents.work(0); 5691 } 5692 5693 set_par_threads(0); 5694 5695 // Closure to test whether a referent is alive. 5696 G1STWIsAliveClosure is_alive(this); 5697 5698 // Even when parallel reference processing is enabled, the processing 5699 // of JNI refs is serial and performed serially by the current thread 5700 // rather than by a worker. The following PSS will be used for processing 5701 // JNI refs. 5702 5703 // Use only a single queue for this PSS. 5704 G1ParScanThreadState pss(this, 0); 5705 5706 // We do not embed a reference processor in the copying/scanning 5707 // closures while we're actually processing the discovered 5708 // reference objects. 5709 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL); 5710 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5711 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL); 5712 5713 pss.set_evac_closure(&scan_evac_cl); 5714 pss.set_evac_failure_closure(&evac_failure_cl); 5715 pss.set_partial_scan_closure(&partial_scan_cl); 5716 5717 assert(pss.refs()->is_empty(), "pre-condition"); 5718 5719 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5720 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL); 5721 5722 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5723 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL); 5724 5725 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5726 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5727 5728 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5729 // We also need to mark copied objects. 5730 copy_non_heap_cl = ©_mark_non_heap_cl; 5731 copy_metadata_cl = ©_mark_metadata_cl; 5732 } 5733 5734 // Keep alive closure. 5735 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss); 5736 5737 // Serial Complete GC closure 5738 G1STWDrainQueueClosure drain_queue(this, &pss); 5739 5740 // Setup the soft refs policy... 5741 rp->setup_policy(false); 5742 5743 ReferenceProcessorStats stats; 5744 if (!rp->processing_is_mt()) { 5745 // Serial reference processing... 5746 stats = rp->process_discovered_references(&is_alive, 5747 &keep_alive, 5748 &drain_queue, 5749 NULL, 5750 _gc_timer_stw); 5751 } else { 5752 // Parallel reference processing 5753 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5754 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5755 5756 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5757 stats = rp->process_discovered_references(&is_alive, 5758 &keep_alive, 5759 &drain_queue, 5760 &par_task_executor, 5761 _gc_timer_stw); 5762 } 5763 5764 _gc_tracer_stw->report_gc_reference_stats(stats); 5765 // We have completed copying any necessary live referent objects 5766 // (that were not copied during the actual pause) so we can 5767 // retire any active alloc buffers 5768 pss.retire_alloc_buffers(); 5769 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5770 5771 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5772 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5773 } 5774 5775 // Weak Reference processing during an evacuation pause (part 2). 5776 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5777 double ref_enq_start = os::elapsedTime(); 5778 5779 ReferenceProcessor* rp = _ref_processor_stw; 5780 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5781 5782 // Now enqueue any remaining on the discovered lists on to 5783 // the pending list. 5784 if (!rp->processing_is_mt()) { 5785 // Serial reference processing... 5786 rp->enqueue_discovered_references(); 5787 } else { 5788 // Parallel reference enqueueing 5789 5790 assert(no_of_gc_workers == workers()->active_workers(), 5791 "Need to reset active workers"); 5792 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5793 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5794 5795 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5796 rp->enqueue_discovered_references(&par_task_executor); 5797 } 5798 5799 rp->verify_no_references_recorded(); 5800 assert(!rp->discovery_enabled(), "should have been disabled"); 5801 5802 // FIXME 5803 // CM's reference processing also cleans up the string and symbol tables. 5804 // Should we do that here also? We could, but it is a serial operation 5805 // and could significantly increase the pause time. 5806 5807 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5808 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5809 } 5810 5811 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5812 _expand_heap_after_alloc_failure = true; 5813 _evacuation_failed = false; 5814 5815 // Should G1EvacuationFailureALot be in effect for this GC? 5816 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5817 5818 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5819 5820 // Disable the hot card cache. 5821 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5822 hot_card_cache->reset_hot_cache_claimed_index(); 5823 hot_card_cache->set_use_cache(false); 5824 5825 uint n_workers; 5826 if (G1CollectedHeap::use_parallel_gc_threads()) { 5827 n_workers = 5828 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5829 workers()->active_workers(), 5830 Threads::number_of_non_daemon_threads()); 5831 assert(UseDynamicNumberOfGCThreads || 5832 n_workers == workers()->total_workers(), 5833 "If not dynamic should be using all the workers"); 5834 workers()->set_active_workers(n_workers); 5835 set_par_threads(n_workers); 5836 } else { 5837 assert(n_par_threads() == 0, 5838 "Should be the original non-parallel value"); 5839 n_workers = 1; 5840 } 5841 5842 G1ParTask g1_par_task(this, _task_queues); 5843 5844 init_for_evac_failure(NULL); 5845 5846 rem_set()->prepare_for_younger_refs_iterate(true); 5847 5848 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5849 double start_par_time_sec = os::elapsedTime(); 5850 double end_par_time_sec; 5851 5852 { 5853 StrongRootsScope srs(this); 5854 5855 if (G1CollectedHeap::use_parallel_gc_threads()) { 5856 // The individual threads will set their evac-failure closures. 5857 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5858 // These tasks use ShareHeap::_process_strong_tasks 5859 assert(UseDynamicNumberOfGCThreads || 5860 workers()->active_workers() == workers()->total_workers(), 5861 "If not dynamic should be using all the workers"); 5862 workers()->run_task(&g1_par_task); 5863 } else { 5864 g1_par_task.set_for_termination(n_workers); 5865 g1_par_task.work(0); 5866 } 5867 end_par_time_sec = os::elapsedTime(); 5868 5869 // Closing the inner scope will execute the destructor 5870 // for the StrongRootsScope object. We record the current 5871 // elapsed time before closing the scope so that time 5872 // taken for the SRS destructor is NOT included in the 5873 // reported parallel time. 5874 } 5875 5876 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5877 g1_policy()->phase_times()->record_par_time(par_time_ms); 5878 5879 double code_root_fixup_time_ms = 5880 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5881 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5882 5883 set_par_threads(0); 5884 5885 // Process any discovered reference objects - we have 5886 // to do this _before_ we retire the GC alloc regions 5887 // as we may have to copy some 'reachable' referent 5888 // objects (and their reachable sub-graphs) that were 5889 // not copied during the pause. 5890 process_discovered_references(n_workers); 5891 5892 // Weak root processing. 5893 { 5894 G1STWIsAliveClosure is_alive(this); 5895 G1KeepAliveClosure keep_alive(this); 5896 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5897 } 5898 5899 release_gc_alloc_regions(n_workers, evacuation_info); 5900 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5901 5902 // Reset and re-enable the hot card cache. 5903 // Note the counts for the cards in the regions in the 5904 // collection set are reset when the collection set is freed. 5905 hot_card_cache->reset_hot_cache(); 5906 hot_card_cache->set_use_cache(true); 5907 5908 // Migrate the strong code roots attached to each region in 5909 // the collection set. Ideally we would like to do this 5910 // after we have finished the scanning/evacuation of the 5911 // strong code roots for a particular heap region. 5912 migrate_strong_code_roots(); 5913 5914 if (g1_policy()->during_initial_mark_pause()) { 5915 // Reset the claim values set during marking the strong code roots 5916 reset_heap_region_claim_values(); 5917 } 5918 5919 finalize_for_evac_failure(); 5920 5921 if (evacuation_failed()) { 5922 remove_self_forwarding_pointers(); 5923 5924 // Reset the G1EvacuationFailureALot counters and flags 5925 // Note: the values are reset only when an actual 5926 // evacuation failure occurs. 5927 NOT_PRODUCT(reset_evacuation_should_fail();) 5928 } 5929 5930 // Enqueue any remaining references remaining on the STW 5931 // reference processor's discovered lists. We need to do 5932 // this after the card table is cleaned (and verified) as 5933 // the act of enqueueing entries on to the pending list 5934 // will log these updates (and dirty their associated 5935 // cards). We need these updates logged to update any 5936 // RSets. 5937 enqueue_discovered_references(n_workers); 5938 5939 if (G1DeferredRSUpdate) { 5940 RedirtyLoggedCardTableEntryFastClosure redirty; 5941 dirty_card_queue_set().set_closure(&redirty); 5942 dirty_card_queue_set().apply_closure_to_all_completed_buffers(); 5943 5944 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5945 dcq.merge_bufferlists(&dirty_card_queue_set()); 5946 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5947 } 5948 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5949 } 5950 5951 void G1CollectedHeap::free_region(HeapRegion* hr, 5952 FreeRegionList* free_list, 5953 bool par) { 5954 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5955 assert(!hr->is_empty(), "the region should not be empty"); 5956 assert(free_list != NULL, "pre-condition"); 5957 5958 // Clear the card counts for this region. 5959 // Note: we only need to do this if the region is not young 5960 // (since we don't refine cards in young regions). 5961 if (!hr->is_young()) { 5962 _cg1r->hot_card_cache()->reset_card_counts(hr); 5963 } 5964 hr->hr_clear(par, true /* clear_space */); 5965 free_list->add_as_head(hr); 5966 } 5967 5968 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5969 FreeRegionList* free_list, 5970 bool par) { 5971 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5972 assert(free_list != NULL, "pre-condition"); 5973 5974 size_t hr_capacity = hr->capacity(); 5975 // We need to read this before we make the region non-humongous, 5976 // otherwise the information will be gone. 5977 uint last_index = hr->last_hc_index(); 5978 hr->set_notHumongous(); 5979 free_region(hr, free_list, par); 5980 5981 uint i = hr->hrs_index() + 1; 5982 while (i < last_index) { 5983 HeapRegion* curr_hr = region_at(i); 5984 assert(curr_hr->continuesHumongous(), "invariant"); 5985 curr_hr->set_notHumongous(); 5986 free_region(curr_hr, free_list, par); 5987 i += 1; 5988 } 5989 } 5990 5991 void G1CollectedHeap::remove_from_sets(const HeapRegionSetCount& old_regions_removed, 5992 const HeapRegionSetCount& humongous_regions_removed) { 5993 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5994 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5995 _old_set.bulk_remove(old_regions_removed); 5996 _humongous_set.bulk_remove(humongous_regions_removed); 5997 } 5998 5999 } 6000 6001 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 6002 assert(list != NULL, "list can't be null"); 6003 if (!list->is_empty()) { 6004 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6005 _free_list.add_as_head(list); 6006 } 6007 } 6008 6009 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6010 assert(_summary_bytes_used >= bytes, 6011 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 6012 _summary_bytes_used, bytes)); 6013 _summary_bytes_used -= bytes; 6014 } 6015 6016 void G1CollectedHeap::decrement_summary_bytes_mt(size_t bytes) { 6017 if (bytes > 0) { 6018 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 6019 decrement_summary_bytes(bytes); 6020 } 6021 } 6022 6023 class G1ParCleanupCTTask : public AbstractGangTask { 6024 G1SATBCardTableModRefBS* _ct_bs; 6025 G1CollectedHeap* _g1h; 6026 HeapRegion* volatile _su_head; 6027 public: 6028 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6029 G1CollectedHeap* g1h) : 6030 AbstractGangTask("G1 Par Cleanup CT Task"), 6031 _ct_bs(ct_bs), _g1h(g1h) { } 6032 6033 void work(uint worker_id) { 6034 HeapRegion* r; 6035 while (r = _g1h->pop_dirty_cards_region()) { 6036 clear_cards(r); 6037 } 6038 } 6039 6040 void clear_cards(HeapRegion* r) { 6041 // Cards of the survivors should have already been dirtied. 6042 if (!r->is_survivor()) { 6043 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6044 } 6045 } 6046 }; 6047 6048 #ifndef PRODUCT 6049 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6050 G1CollectedHeap* _g1h; 6051 G1SATBCardTableModRefBS* _ct_bs; 6052 public: 6053 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6054 : _g1h(g1h), _ct_bs(ct_bs) { } 6055 virtual bool doHeapRegion(HeapRegion* r) { 6056 if (r->is_survivor()) { 6057 _g1h->verify_dirty_region(r); 6058 } else { 6059 _g1h->verify_not_dirty_region(r); 6060 } 6061 return false; 6062 } 6063 }; 6064 6065 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6066 // All of the region should be clean. 6067 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6068 MemRegion mr(hr->bottom(), hr->end()); 6069 ct_bs->verify_not_dirty_region(mr); 6070 } 6071 6072 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6073 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6074 // dirty allocated blocks as they allocate them. The thread that 6075 // retires each region and replaces it with a new one will do a 6076 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6077 // not dirty that area (one less thing to have to do while holding 6078 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6079 // is dirty. 6080 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6081 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6082 if (hr->is_young()) { 6083 ct_bs->verify_g1_young_region(mr); 6084 } else { 6085 ct_bs->verify_dirty_region(mr); 6086 } 6087 } 6088 6089 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6090 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6091 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6092 verify_dirty_region(hr); 6093 } 6094 } 6095 6096 void G1CollectedHeap::verify_dirty_young_regions() { 6097 verify_dirty_young_list(_young_list->first_region()); 6098 } 6099 #endif 6100 6101 void G1CollectedHeap::cleanUpCardTable() { 6102 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6103 double start = os::elapsedTime(); 6104 6105 { 6106 // Iterate over the dirty cards region list. 6107 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6108 6109 if (G1CollectedHeap::use_parallel_gc_threads()) { 6110 set_par_threads(); 6111 workers()->run_task(&cleanup_task); 6112 set_par_threads(0); 6113 } else { 6114 while (_dirty_cards_region_list) { 6115 HeapRegion* r = _dirty_cards_region_list; 6116 cleanup_task.clear_cards(r); 6117 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6118 if (_dirty_cards_region_list == r) { 6119 // The last region. 6120 _dirty_cards_region_list = NULL; 6121 } 6122 r->set_next_dirty_cards_region(NULL); 6123 } 6124 } 6125 #ifndef PRODUCT 6126 if (G1VerifyCTCleanup || VerifyAfterGC) { 6127 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6128 heap_region_iterate(&cleanup_verifier); 6129 } 6130 #endif 6131 } 6132 6133 double elapsed = os::elapsedTime() - start; 6134 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6135 } 6136 6137 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6138 size_t pre_used = 0; 6139 FreeRegionList local_free_list("Local List for CSet Freeing", NULL); 6140 6141 double young_time_ms = 0.0; 6142 double non_young_time_ms = 0.0; 6143 6144 // Since the collection set is a superset of the the young list, 6145 // all we need to do to clear the young list is clear its 6146 // head and length, and unlink any young regions in the code below 6147 _young_list->clear(); 6148 6149 G1CollectorPolicy* policy = g1_policy(); 6150 6151 double start_sec = os::elapsedTime(); 6152 bool non_young = true; 6153 6154 HeapRegion* cur = cs_head; 6155 int age_bound = -1; 6156 size_t rs_lengths = 0; 6157 6158 while (cur != NULL) { 6159 assert(!is_on_master_free_list(cur), "sanity"); 6160 if (non_young) { 6161 if (cur->is_young()) { 6162 double end_sec = os::elapsedTime(); 6163 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6164 non_young_time_ms += elapsed_ms; 6165 6166 start_sec = os::elapsedTime(); 6167 non_young = false; 6168 } 6169 } else { 6170 if (!cur->is_young()) { 6171 double end_sec = os::elapsedTime(); 6172 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6173 young_time_ms += elapsed_ms; 6174 6175 start_sec = os::elapsedTime(); 6176 non_young = true; 6177 } 6178 } 6179 6180 rs_lengths += cur->rem_set()->occupied(); 6181 6182 HeapRegion* next = cur->next_in_collection_set(); 6183 assert(cur->in_collection_set(), "bad CS"); 6184 cur->set_next_in_collection_set(NULL); 6185 cur->set_in_collection_set(false); 6186 6187 if (cur->is_young()) { 6188 int index = cur->young_index_in_cset(); 6189 assert(index != -1, "invariant"); 6190 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6191 size_t words_survived = _surviving_young_words[index]; 6192 cur->record_surv_words_in_group(words_survived); 6193 6194 // At this point the we have 'popped' cur from the collection set 6195 // (linked via next_in_collection_set()) but it is still in the 6196 // young list (linked via next_young_region()). Clear the 6197 // _next_young_region field. 6198 cur->set_next_young_region(NULL); 6199 } else { 6200 int index = cur->young_index_in_cset(); 6201 assert(index == -1, "invariant"); 6202 } 6203 6204 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6205 (!cur->is_young() && cur->young_index_in_cset() == -1), 6206 "invariant" ); 6207 6208 if (!cur->evacuation_failed()) { 6209 MemRegion used_mr = cur->used_region(); 6210 6211 // And the region is empty. 6212 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6213 pre_used += cur->used(); 6214 free_region(cur, &local_free_list, false /* par */); 6215 } else { 6216 cur->uninstall_surv_rate_group(); 6217 if (cur->is_young()) { 6218 cur->set_young_index_in_cset(-1); 6219 } 6220 cur->set_not_young(); 6221 cur->set_evacuation_failed(false); 6222 // The region is now considered to be old. 6223 _old_set.add(cur); 6224 evacuation_info.increment_collectionset_used_after(cur->used()); 6225 } 6226 cur = next; 6227 } 6228 6229 evacuation_info.set_regions_freed(local_free_list.length()); 6230 policy->record_max_rs_lengths(rs_lengths); 6231 policy->cset_regions_freed(); 6232 6233 double end_sec = os::elapsedTime(); 6234 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6235 6236 if (non_young) { 6237 non_young_time_ms += elapsed_ms; 6238 } else { 6239 young_time_ms += elapsed_ms; 6240 } 6241 6242 prepend_to_freelist(&local_free_list); 6243 decrement_summary_bytes(pre_used); 6244 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6245 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6246 } 6247 6248 // This routine is similar to the above but does not record 6249 // any policy statistics or update free lists; we are abandoning 6250 // the current incremental collection set in preparation of a 6251 // full collection. After the full GC we will start to build up 6252 // the incremental collection set again. 6253 // This is only called when we're doing a full collection 6254 // and is immediately followed by the tearing down of the young list. 6255 6256 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6257 HeapRegion* cur = cs_head; 6258 6259 while (cur != NULL) { 6260 HeapRegion* next = cur->next_in_collection_set(); 6261 assert(cur->in_collection_set(), "bad CS"); 6262 cur->set_next_in_collection_set(NULL); 6263 cur->set_in_collection_set(false); 6264 cur->set_young_index_in_cset(-1); 6265 cur = next; 6266 } 6267 } 6268 6269 void G1CollectedHeap::set_free_regions_coming() { 6270 if (G1ConcRegionFreeingVerbose) { 6271 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6272 "setting free regions coming"); 6273 } 6274 6275 assert(!free_regions_coming(), "pre-condition"); 6276 _free_regions_coming = true; 6277 } 6278 6279 void G1CollectedHeap::reset_free_regions_coming() { 6280 assert(free_regions_coming(), "pre-condition"); 6281 6282 { 6283 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6284 _free_regions_coming = false; 6285 SecondaryFreeList_lock->notify_all(); 6286 } 6287 6288 if (G1ConcRegionFreeingVerbose) { 6289 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6290 "reset free regions coming"); 6291 } 6292 } 6293 6294 void G1CollectedHeap::wait_while_free_regions_coming() { 6295 // Most of the time we won't have to wait, so let's do a quick test 6296 // first before we take the lock. 6297 if (!free_regions_coming()) { 6298 return; 6299 } 6300 6301 if (G1ConcRegionFreeingVerbose) { 6302 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6303 "waiting for free regions"); 6304 } 6305 6306 { 6307 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6308 while (free_regions_coming()) { 6309 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6310 } 6311 } 6312 6313 if (G1ConcRegionFreeingVerbose) { 6314 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6315 "done waiting for free regions"); 6316 } 6317 } 6318 6319 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6320 assert(heap_lock_held_for_gc(), 6321 "the heap lock should already be held by or for this thread"); 6322 _young_list->push_region(hr); 6323 } 6324 6325 class NoYoungRegionsClosure: public HeapRegionClosure { 6326 private: 6327 bool _success; 6328 public: 6329 NoYoungRegionsClosure() : _success(true) { } 6330 bool doHeapRegion(HeapRegion* r) { 6331 if (r->is_young()) { 6332 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6333 r->bottom(), r->end()); 6334 _success = false; 6335 } 6336 return false; 6337 } 6338 bool success() { return _success; } 6339 }; 6340 6341 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6342 bool ret = _young_list->check_list_empty(check_sample); 6343 6344 if (check_heap) { 6345 NoYoungRegionsClosure closure; 6346 heap_region_iterate(&closure); 6347 ret = ret && closure.success(); 6348 } 6349 6350 return ret; 6351 } 6352 6353 class TearDownRegionSetsClosure : public HeapRegionClosure { 6354 private: 6355 HeapRegionSet *_old_set; 6356 6357 public: 6358 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6359 6360 bool doHeapRegion(HeapRegion* r) { 6361 if (r->is_empty()) { 6362 // We ignore empty regions, we'll empty the free list afterwards 6363 } else if (r->is_young()) { 6364 // We ignore young regions, we'll empty the young list afterwards 6365 } else if (r->isHumongous()) { 6366 // We ignore humongous regions, we're not tearing down the 6367 // humongous region set 6368 } else { 6369 // The rest should be old 6370 _old_set->remove(r); 6371 } 6372 return false; 6373 } 6374 6375 ~TearDownRegionSetsClosure() { 6376 assert(_old_set->is_empty(), "post-condition"); 6377 } 6378 }; 6379 6380 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6381 assert_at_safepoint(true /* should_be_vm_thread */); 6382 6383 if (!free_list_only) { 6384 TearDownRegionSetsClosure cl(&_old_set); 6385 heap_region_iterate(&cl); 6386 6387 // Need to do this after the heap iteration to be able to 6388 // recognize the young regions and ignore them during the iteration. 6389 _young_list->empty_list(); 6390 } 6391 _free_list.remove_all(); 6392 } 6393 6394 class RebuildRegionSetsClosure : public HeapRegionClosure { 6395 private: 6396 bool _free_list_only; 6397 HeapRegionSet* _old_set; 6398 FreeRegionList* _free_list; 6399 size_t _total_used; 6400 6401 public: 6402 RebuildRegionSetsClosure(bool free_list_only, 6403 HeapRegionSet* old_set, FreeRegionList* free_list) : 6404 _free_list_only(free_list_only), 6405 _old_set(old_set), _free_list(free_list), _total_used(0) { 6406 assert(_free_list->is_empty(), "pre-condition"); 6407 if (!free_list_only) { 6408 assert(_old_set->is_empty(), "pre-condition"); 6409 } 6410 } 6411 6412 bool doHeapRegion(HeapRegion* r) { 6413 if (r->continuesHumongous()) { 6414 return false; 6415 } 6416 6417 if (r->is_empty()) { 6418 // Add free regions to the free list 6419 _free_list->add_as_tail(r); 6420 } else if (!_free_list_only) { 6421 assert(!r->is_young(), "we should not come across young regions"); 6422 6423 if (r->isHumongous()) { 6424 // We ignore humongous regions, we left the humongous set unchanged 6425 } else { 6426 // The rest should be old, add them to the old set 6427 _old_set->add(r); 6428 } 6429 _total_used += r->used(); 6430 } 6431 6432 return false; 6433 } 6434 6435 size_t total_used() { 6436 return _total_used; 6437 } 6438 }; 6439 6440 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6441 assert_at_safepoint(true /* should_be_vm_thread */); 6442 6443 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6444 heap_region_iterate(&cl); 6445 6446 if (!free_list_only) { 6447 _summary_bytes_used = cl.total_used(); 6448 } 6449 assert(_summary_bytes_used == recalculate_used(), 6450 err_msg("inconsistent _summary_bytes_used, " 6451 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6452 _summary_bytes_used, recalculate_used())); 6453 } 6454 6455 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6456 _refine_cte_cl->set_concurrent(concurrent); 6457 } 6458 6459 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6460 HeapRegion* hr = heap_region_containing(p); 6461 if (hr == NULL) { 6462 return false; 6463 } else { 6464 return hr->is_in(p); 6465 } 6466 } 6467 6468 // Methods for the mutator alloc region 6469 6470 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6471 bool force) { 6472 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6473 assert(!force || g1_policy()->can_expand_young_list(), 6474 "if force is true we should be able to expand the young list"); 6475 bool young_list_full = g1_policy()->is_young_list_full(); 6476 if (force || !young_list_full) { 6477 HeapRegion* new_alloc_region = new_region(word_size, 6478 false /* do_expand */); 6479 if (new_alloc_region != NULL) { 6480 set_region_short_lived_locked(new_alloc_region); 6481 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6482 return new_alloc_region; 6483 } 6484 } 6485 return NULL; 6486 } 6487 6488 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6489 size_t allocated_bytes) { 6490 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6491 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6492 6493 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6494 _summary_bytes_used += allocated_bytes; 6495 _hr_printer.retire(alloc_region); 6496 // We update the eden sizes here, when the region is retired, 6497 // instead of when it's allocated, since this is the point that its 6498 // used space has been recored in _summary_bytes_used. 6499 g1mm()->update_eden_size(); 6500 } 6501 6502 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6503 bool force) { 6504 return _g1h->new_mutator_alloc_region(word_size, force); 6505 } 6506 6507 void G1CollectedHeap::set_par_threads() { 6508 // Don't change the number of workers. Use the value previously set 6509 // in the workgroup. 6510 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6511 uint n_workers = workers()->active_workers(); 6512 assert(UseDynamicNumberOfGCThreads || 6513 n_workers == workers()->total_workers(), 6514 "Otherwise should be using the total number of workers"); 6515 if (n_workers == 0) { 6516 assert(false, "Should have been set in prior evacuation pause."); 6517 n_workers = ParallelGCThreads; 6518 workers()->set_active_workers(n_workers); 6519 } 6520 set_par_threads(n_workers); 6521 } 6522 6523 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6524 size_t allocated_bytes) { 6525 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6526 } 6527 6528 // Methods for the GC alloc regions 6529 6530 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6531 uint count, 6532 GCAllocPurpose ap) { 6533 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6534 6535 if (count < g1_policy()->max_regions(ap)) { 6536 HeapRegion* new_alloc_region = new_region(word_size, 6537 true /* do_expand */); 6538 if (new_alloc_region != NULL) { 6539 // We really only need to do this for old regions given that we 6540 // should never scan survivors. But it doesn't hurt to do it 6541 // for survivors too. 6542 new_alloc_region->set_saved_mark(); 6543 if (ap == GCAllocForSurvived) { 6544 new_alloc_region->set_survivor(); 6545 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6546 } else { 6547 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6548 } 6549 bool during_im = g1_policy()->during_initial_mark_pause(); 6550 new_alloc_region->note_start_of_copying(during_im); 6551 return new_alloc_region; 6552 } else { 6553 g1_policy()->note_alloc_region_limit_reached(ap); 6554 } 6555 } 6556 return NULL; 6557 } 6558 6559 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6560 size_t allocated_bytes, 6561 GCAllocPurpose ap) { 6562 bool during_im = g1_policy()->during_initial_mark_pause(); 6563 alloc_region->note_end_of_copying(during_im); 6564 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6565 if (ap == GCAllocForSurvived) { 6566 young_list()->add_survivor_region(alloc_region); 6567 } else { 6568 _old_set.add(alloc_region); 6569 } 6570 _hr_printer.retire(alloc_region); 6571 } 6572 6573 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6574 bool force) { 6575 assert(!force, "not supported for GC alloc regions"); 6576 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6577 } 6578 6579 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6580 size_t allocated_bytes) { 6581 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6582 GCAllocForSurvived); 6583 } 6584 6585 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6586 bool force) { 6587 assert(!force, "not supported for GC alloc regions"); 6588 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6589 } 6590 6591 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6592 size_t allocated_bytes) { 6593 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6594 GCAllocForTenured); 6595 } 6596 // Heap region set verification 6597 6598 class VerifyRegionListsClosure : public HeapRegionClosure { 6599 private: 6600 HeapRegionSet* _old_set; 6601 HeapRegionSet* _humongous_set; 6602 FreeRegionList* _free_list; 6603 6604 public: 6605 HeapRegionSetCount _old_count; 6606 HeapRegionSetCount _humongous_count; 6607 HeapRegionSetCount _free_count; 6608 6609 VerifyRegionListsClosure(HeapRegionSet* old_set, 6610 HeapRegionSet* humongous_set, 6611 FreeRegionList* free_list) : 6612 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list), 6613 _old_count(), _humongous_count(), _free_count(){ } 6614 6615 bool doHeapRegion(HeapRegion* hr) { 6616 if (hr->continuesHumongous()) { 6617 return false; 6618 } 6619 6620 if (hr->is_young()) { 6621 // TODO 6622 } else if (hr->startsHumongous()) { 6623 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num())); 6624 _humongous_count.increment(1u, hr->capacity()); 6625 } else if (hr->is_empty()) { 6626 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num())); 6627 _free_count.increment(1u, hr->capacity()); 6628 } else { 6629 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num())); 6630 _old_count.increment(1u, hr->capacity()); 6631 } 6632 return false; 6633 } 6634 }; 6635 6636 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6637 HeapWord* bottom) { 6638 HeapWord* end = bottom + HeapRegion::GrainWords; 6639 MemRegion mr(bottom, end); 6640 assert(_g1_reserved.contains(mr), "invariant"); 6641 // This might return NULL if the allocation fails 6642 return new HeapRegion(hrs_index, _bot_shared, mr); 6643 } 6644 6645 void G1CollectedHeap::verify_region_sets() { 6646 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6647 6648 // First, check the explicit lists. 6649 _free_list.verify_list(); 6650 { 6651 // Given that a concurrent operation might be adding regions to 6652 // the secondary free list we have to take the lock before 6653 // verifying it. 6654 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6655 _secondary_free_list.verify_list(); 6656 } 6657 6658 // If a concurrent region freeing operation is in progress it will 6659 // be difficult to correctly attributed any free regions we come 6660 // across to the correct free list given that they might belong to 6661 // one of several (free_list, secondary_free_list, any local lists, 6662 // etc.). So, if that's the case we will skip the rest of the 6663 // verification operation. Alternatively, waiting for the concurrent 6664 // operation to complete will have a non-trivial effect on the GC's 6665 // operation (no concurrent operation will last longer than the 6666 // interval between two calls to verification) and it might hide 6667 // any issues that we would like to catch during testing. 6668 if (free_regions_coming()) { 6669 return; 6670 } 6671 6672 // Make sure we append the secondary_free_list on the free_list so 6673 // that all free regions we will come across can be safely 6674 // attributed to the free_list. 6675 append_secondary_free_list_if_not_empty_with_lock(); 6676 6677 // Finally, make sure that the region accounting in the lists is 6678 // consistent with what we see in the heap. 6679 6680 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6681 heap_region_iterate(&cl); 6682 6683 guarantee(_old_set.length() == cl._old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", _old_set.length(), cl._old_count.length())); 6684 guarantee(_old_set.total_capacity_bytes() == cl._old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6685 _old_set.total_capacity_bytes(), cl._old_count.capacity())); 6686 6687 guarantee(_humongous_set.length() == cl._humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", _humongous_set.length(), cl._humongous_count.length())); 6688 guarantee(_humongous_set.total_capacity_bytes() == cl._humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6689 _humongous_set.total_capacity_bytes(), cl._humongous_count.capacity())); 6690 6691 guarantee(_free_list.length() == cl._free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", _free_list.length(), cl._free_count.length())); 6692 guarantee(_free_list.total_capacity_bytes() == cl._free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6693 _free_list.total_capacity_bytes(), cl._free_count.capacity())); 6694 } 6695 6696 // Optimized nmethod scanning 6697 6698 class RegisterNMethodOopClosure: public OopClosure { 6699 G1CollectedHeap* _g1h; 6700 nmethod* _nm; 6701 6702 template <class T> void do_oop_work(T* p) { 6703 T heap_oop = oopDesc::load_heap_oop(p); 6704 if (!oopDesc::is_null(heap_oop)) { 6705 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6706 HeapRegion* hr = _g1h->heap_region_containing(obj); 6707 assert(!hr->continuesHumongous(), 6708 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6709 " starting at "HR_FORMAT, 6710 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6711 6712 // HeapRegion::add_strong_code_root() avoids adding duplicate 6713 // entries but having duplicates is OK since we "mark" nmethods 6714 // as visited when we scan the strong code root lists during the GC. 6715 hr->add_strong_code_root(_nm); 6716 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 6717 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 6718 _nm, HR_FORMAT_PARAMS(hr))); 6719 } 6720 } 6721 6722 public: 6723 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6724 _g1h(g1h), _nm(nm) {} 6725 6726 void do_oop(oop* p) { do_oop_work(p); } 6727 void do_oop(narrowOop* p) { do_oop_work(p); } 6728 }; 6729 6730 class UnregisterNMethodOopClosure: public OopClosure { 6731 G1CollectedHeap* _g1h; 6732 nmethod* _nm; 6733 6734 template <class T> void do_oop_work(T* p) { 6735 T heap_oop = oopDesc::load_heap_oop(p); 6736 if (!oopDesc::is_null(heap_oop)) { 6737 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6738 HeapRegion* hr = _g1h->heap_region_containing(obj); 6739 assert(!hr->continuesHumongous(), 6740 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6741 " starting at "HR_FORMAT, 6742 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6743 6744 hr->remove_strong_code_root(_nm); 6745 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 6746 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 6747 _nm, HR_FORMAT_PARAMS(hr))); 6748 } 6749 } 6750 6751 public: 6752 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6753 _g1h(g1h), _nm(nm) {} 6754 6755 void do_oop(oop* p) { do_oop_work(p); } 6756 void do_oop(narrowOop* p) { do_oop_work(p); } 6757 }; 6758 6759 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6760 CollectedHeap::register_nmethod(nm); 6761 6762 guarantee(nm != NULL, "sanity"); 6763 RegisterNMethodOopClosure reg_cl(this, nm); 6764 nm->oops_do(®_cl); 6765 } 6766 6767 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6768 CollectedHeap::unregister_nmethod(nm); 6769 6770 guarantee(nm != NULL, "sanity"); 6771 UnregisterNMethodOopClosure reg_cl(this, nm); 6772 nm->oops_do(®_cl, true); 6773 } 6774 6775 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 6776 public: 6777 bool doHeapRegion(HeapRegion *hr) { 6778 assert(!hr->isHumongous(), 6779 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 6780 HR_FORMAT_PARAMS(hr))); 6781 hr->migrate_strong_code_roots(); 6782 return false; 6783 } 6784 }; 6785 6786 void G1CollectedHeap::migrate_strong_code_roots() { 6787 MigrateCodeRootsHeapRegionClosure cl; 6788 double migrate_start = os::elapsedTime(); 6789 collection_set_iterate(&cl); 6790 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 6791 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 6792 } 6793 6794 // Mark all the code roots that point into regions *not* in the 6795 // collection set. 6796 // 6797 // Note we do not want to use a "marking" CodeBlobToOopClosure while 6798 // walking the the code roots lists of regions not in the collection 6799 // set. Suppose we have an nmethod (M) that points to objects in two 6800 // separate regions - one in the collection set (R1) and one not (R2). 6801 // Using a "marking" CodeBlobToOopClosure here would result in "marking" 6802 // nmethod M when walking the code roots for R1. When we come to scan 6803 // the code roots for R2, we would see that M is already marked and it 6804 // would be skipped and the objects in R2 that are referenced from M 6805 // would not be evacuated. 6806 6807 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 6808 6809 class MarkStrongCodeRootOopClosure: public OopClosure { 6810 ConcurrentMark* _cm; 6811 HeapRegion* _hr; 6812 uint _worker_id; 6813 6814 template <class T> void do_oop_work(T* p) { 6815 T heap_oop = oopDesc::load_heap_oop(p); 6816 if (!oopDesc::is_null(heap_oop)) { 6817 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6818 // Only mark objects in the region (which is assumed 6819 // to be not in the collection set). 6820 if (_hr->is_in(obj)) { 6821 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 6822 } 6823 } 6824 } 6825 6826 public: 6827 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) : 6828 _cm(cm), _hr(hr), _worker_id(worker_id) { 6829 assert(!_hr->in_collection_set(), "sanity"); 6830 } 6831 6832 void do_oop(narrowOop* p) { do_oop_work(p); } 6833 void do_oop(oop* p) { do_oop_work(p); } 6834 }; 6835 6836 MarkStrongCodeRootOopClosure _oop_cl; 6837 6838 public: 6839 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id): 6840 _oop_cl(cm, hr, worker_id) {} 6841 6842 void do_code_blob(CodeBlob* cb) { 6843 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 6844 if (nm != NULL) { 6845 nm->oops_do(&_oop_cl); 6846 } 6847 } 6848 }; 6849 6850 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure { 6851 G1CollectedHeap* _g1h; 6852 uint _worker_id; 6853 6854 public: 6855 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) : 6856 _g1h(g1h), _worker_id(worker_id) {} 6857 6858 bool doHeapRegion(HeapRegion *hr) { 6859 HeapRegionRemSet* hrrs = hr->rem_set(); 6860 if (hr->continuesHumongous()) { 6861 // Code roots should never be attached to a continuation of a humongous region 6862 assert(hrrs->strong_code_roots_list_length() == 0, 6863 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT 6864 " starting at "HR_FORMAT", but has "INT32_FORMAT, 6865 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()), 6866 hrrs->strong_code_roots_list_length())); 6867 return false; 6868 } 6869 6870 if (hr->in_collection_set()) { 6871 // Don't mark code roots into regions in the collection set here. 6872 // They will be marked when we scan them. 6873 return false; 6874 } 6875 6876 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id); 6877 hr->strong_code_roots_do(&cb_cl); 6878 return false; 6879 } 6880 }; 6881 6882 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) { 6883 MarkStrongCodeRootsHRClosure cl(this, worker_id); 6884 if (G1CollectedHeap::use_parallel_gc_threads()) { 6885 heap_region_par_iterate_chunked(&cl, 6886 worker_id, 6887 workers()->active_workers(), 6888 HeapRegion::ParMarkRootClaimValue); 6889 } else { 6890 heap_region_iterate(&cl); 6891 } 6892 } 6893 6894 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6895 G1CollectedHeap* _g1h; 6896 6897 public: 6898 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6899 _g1h(g1h) {} 6900 6901 void do_code_blob(CodeBlob* cb) { 6902 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6903 if (nm == NULL) { 6904 return; 6905 } 6906 6907 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) { 6908 _g1h->register_nmethod(nm); 6909 } 6910 } 6911 }; 6912 6913 void G1CollectedHeap::rebuild_strong_code_roots() { 6914 RebuildStrongCodeRootClosure blob_cl(this); 6915 CodeCache::blobs_do(&blob_cl); 6916 }