1 /* 2 * Copyright (c) 2001, 2013, 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/icBuffer.hpp" 27 #include "gc_implementation/g1/bufferingOopClosure.hpp" 28 #include "gc_implementation/g1/concurrentG1Refine.hpp" 29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 33 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 34 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 35 #include "gc_implementation/g1/g1EvacFailure.hpp" 36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 37 #include "gc_implementation/g1/g1Log.hpp" 38 #include "gc_implementation/g1/g1MarkSweep.hpp" 39 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 40 #include "gc_implementation/g1/g1RemSet.inline.hpp" 41 #include "gc_implementation/g1/g1YCTypes.hpp" 42 #include "gc_implementation/g1/heapRegion.inline.hpp" 43 #include "gc_implementation/g1/heapRegionRemSet.hpp" 44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 45 #include "gc_implementation/g1/vm_operations_g1.hpp" 46 #include "gc_implementation/shared/gcHeapSummary.hpp" 47 #include "gc_implementation/shared/gcTimer.hpp" 48 #include "gc_implementation/shared/gcTrace.hpp" 49 #include "gc_implementation/shared/gcTraceTime.hpp" 50 #include "gc_implementation/shared/isGCActiveMark.hpp" 51 #include "memory/gcLocker.inline.hpp" 52 #include "memory/genOopClosures.inline.hpp" 53 #include "memory/generationSpec.hpp" 54 #include "memory/referenceProcessor.hpp" 55 #include "oops/oop.inline.hpp" 56 #include "oops/oop.pcgc.inline.hpp" 57 #include "runtime/aprofiler.hpp" 58 #include "runtime/vmThread.hpp" 59 60 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 61 62 // turn it on so that the contents of the young list (scan-only / 63 // to-be-collected) are printed at "strategic" points before / during 64 // / after the collection --- this is useful for debugging 65 #define YOUNG_LIST_VERBOSE 0 66 // CURRENT STATUS 67 // This file is under construction. Search for "FIXME". 68 69 // INVARIANTS/NOTES 70 // 71 // All allocation activity covered by the G1CollectedHeap interface is 72 // serialized by acquiring the HeapLock. This happens in mem_allocate 73 // and allocate_new_tlab, which are the "entry" points to the 74 // allocation code from the rest of the JVM. (Note that this does not 75 // apply to TLAB allocation, which is not part of this interface: it 76 // is done by clients of this interface.) 77 78 // Notes on implementation of parallelism in different tasks. 79 // 80 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 81 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 82 // It does use run_task() which sets _n_workers in the task. 83 // G1ParTask executes g1_process_strong_roots() -> 84 // SharedHeap::process_strong_roots() which calls eventually to 85 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 86 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 87 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 88 // 89 90 // Local to this file. 91 92 class RefineCardTableEntryClosure: public CardTableEntryClosure { 93 SuspendibleThreadSet* _sts; 94 G1RemSet* _g1rs; 95 ConcurrentG1Refine* _cg1r; 96 bool _concurrent; 97 public: 98 RefineCardTableEntryClosure(SuspendibleThreadSet* sts, 99 G1RemSet* g1rs, 100 ConcurrentG1Refine* cg1r) : 101 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true) 102 {} 103 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 104 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false); 105 // This path is executed by the concurrent refine or mutator threads, 106 // concurrently, and so we do not care if card_ptr contains references 107 // that point into the collection set. 108 assert(!oops_into_cset, "should be"); 109 110 if (_concurrent && _sts->should_yield()) { 111 // Caller will actually yield. 112 return false; 113 } 114 // Otherwise, we finished successfully; return true. 115 return true; 116 } 117 void set_concurrent(bool b) { _concurrent = b; } 118 }; 119 120 121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 122 int _calls; 123 G1CollectedHeap* _g1h; 124 CardTableModRefBS* _ctbs; 125 int _histo[256]; 126 public: 127 ClearLoggedCardTableEntryClosure() : 128 _calls(0) 129 { 130 _g1h = G1CollectedHeap::heap(); 131 _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); 132 for (int i = 0; i < 256; i++) _histo[i] = 0; 133 } 134 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 135 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 136 _calls++; 137 unsigned char* ujb = (unsigned char*)card_ptr; 138 int ind = (int)(*ujb); 139 _histo[ind]++; 140 *card_ptr = -1; 141 } 142 return true; 143 } 144 int calls() { return _calls; } 145 void print_histo() { 146 gclog_or_tty->print_cr("Card table value histogram:"); 147 for (int i = 0; i < 256; i++) { 148 if (_histo[i] != 0) { 149 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 150 } 151 } 152 } 153 }; 154 155 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { 156 int _calls; 157 G1CollectedHeap* _g1h; 158 CardTableModRefBS* _ctbs; 159 public: 160 RedirtyLoggedCardTableEntryClosure() : 161 _calls(0) 162 { 163 _g1h = G1CollectedHeap::heap(); 164 _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); 165 } 166 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 167 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 168 _calls++; 169 *card_ptr = 0; 170 } 171 return true; 172 } 173 int calls() { return _calls; } 174 }; 175 176 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { 177 public: 178 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 179 *card_ptr = CardTableModRefBS::dirty_card_val(); 180 return true; 181 } 182 }; 183 184 YoungList::YoungList(G1CollectedHeap* g1h) : 185 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 186 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 187 guarantee(check_list_empty(false), "just making sure..."); 188 } 189 190 void YoungList::push_region(HeapRegion *hr) { 191 assert(!hr->is_young(), "should not already be young"); 192 assert(hr->get_next_young_region() == NULL, "cause it should!"); 193 194 hr->set_next_young_region(_head); 195 _head = hr; 196 197 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 198 ++_length; 199 } 200 201 void YoungList::add_survivor_region(HeapRegion* hr) { 202 assert(hr->is_survivor(), "should be flagged as survivor region"); 203 assert(hr->get_next_young_region() == NULL, "cause it should!"); 204 205 hr->set_next_young_region(_survivor_head); 206 if (_survivor_head == NULL) { 207 _survivor_tail = hr; 208 } 209 _survivor_head = hr; 210 ++_survivor_length; 211 } 212 213 void YoungList::empty_list(HeapRegion* list) { 214 while (list != NULL) { 215 HeapRegion* next = list->get_next_young_region(); 216 list->set_next_young_region(NULL); 217 list->uninstall_surv_rate_group(); 218 list->set_not_young(); 219 list = next; 220 } 221 } 222 223 void YoungList::empty_list() { 224 assert(check_list_well_formed(), "young list should be well formed"); 225 226 empty_list(_head); 227 _head = NULL; 228 _length = 0; 229 230 empty_list(_survivor_head); 231 _survivor_head = NULL; 232 _survivor_tail = NULL; 233 _survivor_length = 0; 234 235 _last_sampled_rs_lengths = 0; 236 237 assert(check_list_empty(false), "just making sure..."); 238 } 239 240 bool YoungList::check_list_well_formed() { 241 bool ret = true; 242 243 uint length = 0; 244 HeapRegion* curr = _head; 245 HeapRegion* last = NULL; 246 while (curr != NULL) { 247 if (!curr->is_young()) { 248 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 249 "incorrectly tagged (y: %d, surv: %d)", 250 curr->bottom(), curr->end(), 251 curr->is_young(), curr->is_survivor()); 252 ret = false; 253 } 254 ++length; 255 last = curr; 256 curr = curr->get_next_young_region(); 257 } 258 ret = ret && (length == _length); 259 260 if (!ret) { 261 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 262 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 263 length, _length); 264 } 265 266 return ret; 267 } 268 269 bool YoungList::check_list_empty(bool check_sample) { 270 bool ret = true; 271 272 if (_length != 0) { 273 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 274 _length); 275 ret = false; 276 } 277 if (check_sample && _last_sampled_rs_lengths != 0) { 278 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 279 ret = false; 280 } 281 if (_head != NULL) { 282 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 283 ret = false; 284 } 285 if (!ret) { 286 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 287 } 288 289 return ret; 290 } 291 292 void 293 YoungList::rs_length_sampling_init() { 294 _sampled_rs_lengths = 0; 295 _curr = _head; 296 } 297 298 bool 299 YoungList::rs_length_sampling_more() { 300 return _curr != NULL; 301 } 302 303 void 304 YoungList::rs_length_sampling_next() { 305 assert( _curr != NULL, "invariant" ); 306 size_t rs_length = _curr->rem_set()->occupied(); 307 308 _sampled_rs_lengths += rs_length; 309 310 // The current region may not yet have been added to the 311 // incremental collection set (it gets added when it is 312 // retired as the current allocation region). 313 if (_curr->in_collection_set()) { 314 // Update the collection set policy information for this region 315 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 316 } 317 318 _curr = _curr->get_next_young_region(); 319 if (_curr == NULL) { 320 _last_sampled_rs_lengths = _sampled_rs_lengths; 321 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 322 } 323 } 324 325 void 326 YoungList::reset_auxilary_lists() { 327 guarantee( is_empty(), "young list should be empty" ); 328 assert(check_list_well_formed(), "young list should be well formed"); 329 330 // Add survivor regions to SurvRateGroup. 331 _g1h->g1_policy()->note_start_adding_survivor_regions(); 332 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 333 334 int young_index_in_cset = 0; 335 for (HeapRegion* curr = _survivor_head; 336 curr != NULL; 337 curr = curr->get_next_young_region()) { 338 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 339 340 // The region is a non-empty survivor so let's add it to 341 // the incremental collection set for the next evacuation 342 // pause. 343 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 344 young_index_in_cset += 1; 345 } 346 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 347 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 348 349 _head = _survivor_head; 350 _length = _survivor_length; 351 if (_survivor_head != NULL) { 352 assert(_survivor_tail != NULL, "cause it shouldn't be"); 353 assert(_survivor_length > 0, "invariant"); 354 _survivor_tail->set_next_young_region(NULL); 355 } 356 357 // Don't clear the survivor list handles until the start of 358 // the next evacuation pause - we need it in order to re-tag 359 // the survivor regions from this evacuation pause as 'young' 360 // at the start of the next. 361 362 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 363 364 assert(check_list_well_formed(), "young list should be well formed"); 365 } 366 367 void YoungList::print() { 368 HeapRegion* lists[] = {_head, _survivor_head}; 369 const char* names[] = {"YOUNG", "SURVIVOR"}; 370 371 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 372 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 373 HeapRegion *curr = lists[list]; 374 if (curr == NULL) 375 gclog_or_tty->print_cr(" empty"); 376 while (curr != NULL) { 377 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 378 HR_FORMAT_PARAMS(curr), 379 curr->prev_top_at_mark_start(), 380 curr->next_top_at_mark_start(), 381 curr->age_in_surv_rate_group_cond()); 382 curr = curr->get_next_young_region(); 383 } 384 } 385 386 gclog_or_tty->print_cr(""); 387 } 388 389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 390 { 391 // Claim the right to put the region on the dirty cards region list 392 // by installing a self pointer. 393 HeapRegion* next = hr->get_next_dirty_cards_region(); 394 if (next == NULL) { 395 HeapRegion* res = (HeapRegion*) 396 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 397 NULL); 398 if (res == NULL) { 399 HeapRegion* head; 400 do { 401 // Put the region to the dirty cards region list. 402 head = _dirty_cards_region_list; 403 next = (HeapRegion*) 404 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 405 if (next == head) { 406 assert(hr->get_next_dirty_cards_region() == hr, 407 "hr->get_next_dirty_cards_region() != hr"); 408 if (next == NULL) { 409 // The last region in the list points to itself. 410 hr->set_next_dirty_cards_region(hr); 411 } else { 412 hr->set_next_dirty_cards_region(next); 413 } 414 } 415 } while (next != head); 416 } 417 } 418 } 419 420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 421 { 422 HeapRegion* head; 423 HeapRegion* hr; 424 do { 425 head = _dirty_cards_region_list; 426 if (head == NULL) { 427 return NULL; 428 } 429 HeapRegion* new_head = head->get_next_dirty_cards_region(); 430 if (head == new_head) { 431 // The last region. 432 new_head = NULL; 433 } 434 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 435 head); 436 } while (hr != head); 437 assert(hr != NULL, "invariant"); 438 hr->set_next_dirty_cards_region(NULL); 439 return hr; 440 } 441 442 void G1CollectedHeap::stop_conc_gc_threads() { 443 _cg1r->stop(); 444 _cmThread->stop(); 445 } 446 447 #ifdef ASSERT 448 // A region is added to the collection set as it is retired 449 // so an address p can point to a region which will be in the 450 // collection set but has not yet been retired. This method 451 // therefore is only accurate during a GC pause after all 452 // regions have been retired. It is used for debugging 453 // to check if an nmethod has references to objects that can 454 // be move during a partial collection. Though it can be 455 // inaccurate, it is sufficient for G1 because the conservative 456 // implementation of is_scavengable() for G1 will indicate that 457 // all nmethods must be scanned during a partial collection. 458 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 459 HeapRegion* hr = heap_region_containing(p); 460 return hr != NULL && hr->in_collection_set(); 461 } 462 #endif 463 464 // Returns true if the reference points to an object that 465 // can move in an incremental collection. 466 bool G1CollectedHeap::is_scavengable(const void* p) { 467 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 468 G1CollectorPolicy* g1p = g1h->g1_policy(); 469 HeapRegion* hr = heap_region_containing(p); 470 if (hr == NULL) { 471 // perm gen (or null) 472 return false; 473 } else { 474 return !hr->isHumongous(); 475 } 476 } 477 478 void G1CollectedHeap::check_ct_logs_at_safepoint() { 479 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 480 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); 481 482 // Count the dirty cards at the start. 483 CountNonCleanMemRegionClosure count1(this); 484 ct_bs->mod_card_iterate(&count1); 485 int orig_count = count1.n(); 486 487 // First clear the logged cards. 488 ClearLoggedCardTableEntryClosure clear; 489 dcqs.set_closure(&clear); 490 dcqs.apply_closure_to_all_completed_buffers(); 491 dcqs.iterate_closure_all_threads(false); 492 clear.print_histo(); 493 494 // Now ensure that there's no dirty cards. 495 CountNonCleanMemRegionClosure count2(this); 496 ct_bs->mod_card_iterate(&count2); 497 if (count2.n() != 0) { 498 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 499 count2.n(), orig_count); 500 } 501 guarantee(count2.n() == 0, "Card table should be clean."); 502 503 RedirtyLoggedCardTableEntryClosure redirty; 504 JavaThread::dirty_card_queue_set().set_closure(&redirty); 505 dcqs.apply_closure_to_all_completed_buffers(); 506 dcqs.iterate_closure_all_threads(false); 507 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 508 clear.calls(), orig_count); 509 guarantee(redirty.calls() == clear.calls(), 510 "Or else mechanism is broken."); 511 512 CountNonCleanMemRegionClosure count3(this); 513 ct_bs->mod_card_iterate(&count3); 514 if (count3.n() != orig_count) { 515 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 516 orig_count, count3.n()); 517 guarantee(count3.n() >= orig_count, "Should have restored them all."); 518 } 519 520 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 521 } 522 523 // Private class members. 524 525 G1CollectedHeap* G1CollectedHeap::_g1h; 526 527 // Private methods. 528 529 HeapRegion* 530 G1CollectedHeap::new_region_try_secondary_free_list() { 531 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 532 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 533 if (!_secondary_free_list.is_empty()) { 534 if (G1ConcRegionFreeingVerbose) { 535 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 536 "secondary_free_list has %u entries", 537 _secondary_free_list.length()); 538 } 539 // It looks as if there are free regions available on the 540 // secondary_free_list. Let's move them to the free_list and try 541 // again to allocate from it. 542 append_secondary_free_list(); 543 544 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 545 "empty we should have moved at least one entry to the free_list"); 546 HeapRegion* res = _free_list.remove_head(); 547 if (G1ConcRegionFreeingVerbose) { 548 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 549 "allocated "HR_FORMAT" from secondary_free_list", 550 HR_FORMAT_PARAMS(res)); 551 } 552 return res; 553 } 554 555 // Wait here until we get notified either when (a) there are no 556 // more free regions coming or (b) some regions have been moved on 557 // the secondary_free_list. 558 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 559 } 560 561 if (G1ConcRegionFreeingVerbose) { 562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 563 "could not allocate from secondary_free_list"); 564 } 565 return NULL; 566 } 567 568 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) { 569 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 570 "the only time we use this to allocate a humongous region is " 571 "when we are allocating a single humongous region"); 572 573 HeapRegion* res; 574 if (G1StressConcRegionFreeing) { 575 if (!_secondary_free_list.is_empty()) { 576 if (G1ConcRegionFreeingVerbose) { 577 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 578 "forced to look at the secondary_free_list"); 579 } 580 res = new_region_try_secondary_free_list(); 581 if (res != NULL) { 582 return res; 583 } 584 } 585 } 586 res = _free_list.remove_head_or_null(); 587 if (res == NULL) { 588 if (G1ConcRegionFreeingVerbose) { 589 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 590 "res == NULL, trying the secondary_free_list"); 591 } 592 res = new_region_try_secondary_free_list(); 593 } 594 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 595 // Currently, only attempts to allocate GC alloc regions set 596 // do_expand to true. So, we should only reach here during a 597 // safepoint. If this assumption changes we might have to 598 // reconsider the use of _expand_heap_after_alloc_failure. 599 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 600 601 ergo_verbose1(ErgoHeapSizing, 602 "attempt heap expansion", 603 ergo_format_reason("region allocation request failed") 604 ergo_format_byte("allocation request"), 605 word_size * HeapWordSize); 606 if (expand(word_size * HeapWordSize)) { 607 // Given that expand() succeeded in expanding the heap, and we 608 // always expand the heap by an amount aligned to the heap 609 // region size, the free list should in theory not be empty. So 610 // it would probably be OK to use remove_head(). But the extra 611 // check for NULL is unlikely to be a performance issue here (we 612 // just expanded the heap!) so let's just be conservative and 613 // use remove_head_or_null(). 614 res = _free_list.remove_head_or_null(); 615 } else { 616 _expand_heap_after_alloc_failure = false; 617 } 618 } 619 return res; 620 } 621 622 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 623 size_t word_size) { 624 assert(isHumongous(word_size), "word_size should be humongous"); 625 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 626 627 uint first = G1_NULL_HRS_INDEX; 628 if (num_regions == 1) { 629 // Only one region to allocate, no need to go through the slower 630 // path. The caller will attempt the expansion if this fails, so 631 // let's not try to expand here too. 632 HeapRegion* hr = new_region(word_size, false /* do_expand */); 633 if (hr != NULL) { 634 first = hr->hrs_index(); 635 } else { 636 first = G1_NULL_HRS_INDEX; 637 } 638 } else { 639 // We can't allocate humongous regions while cleanupComplete() is 640 // running, since some of the regions we find to be empty might not 641 // yet be added to the free list and it is not straightforward to 642 // know which list they are on so that we can remove them. Note 643 // that we only need to do this if we need to allocate more than 644 // one region to satisfy the current humongous allocation 645 // request. If we are only allocating one region we use the common 646 // region allocation code (see above). 647 wait_while_free_regions_coming(); 648 append_secondary_free_list_if_not_empty_with_lock(); 649 650 if (free_regions() >= num_regions) { 651 first = _hrs.find_contiguous(num_regions); 652 if (first != G1_NULL_HRS_INDEX) { 653 for (uint i = first; i < first + num_regions; ++i) { 654 HeapRegion* hr = region_at(i); 655 assert(hr->is_empty(), "sanity"); 656 assert(is_on_master_free_list(hr), "sanity"); 657 hr->set_pending_removal(true); 658 } 659 _free_list.remove_all_pending(num_regions); 660 } 661 } 662 } 663 return first; 664 } 665 666 HeapWord* 667 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 668 uint num_regions, 669 size_t word_size) { 670 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 671 assert(isHumongous(word_size), "word_size should be humongous"); 672 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 673 674 // Index of last region in the series + 1. 675 uint last = first + num_regions; 676 677 // We need to initialize the region(s) we just discovered. This is 678 // a bit tricky given that it can happen concurrently with 679 // refinement threads refining cards on these regions and 680 // potentially wanting to refine the BOT as they are scanning 681 // those cards (this can happen shortly after a cleanup; see CR 682 // 6991377). So we have to set up the region(s) carefully and in 683 // a specific order. 684 685 // The word size sum of all the regions we will allocate. 686 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 687 assert(word_size <= word_size_sum, "sanity"); 688 689 // This will be the "starts humongous" region. 690 HeapRegion* first_hr = region_at(first); 691 // The header of the new object will be placed at the bottom of 692 // the first region. 693 HeapWord* new_obj = first_hr->bottom(); 694 // This will be the new end of the first region in the series that 695 // should also match the end of the last region in the series. 696 HeapWord* new_end = new_obj + word_size_sum; 697 // This will be the new top of the first region that will reflect 698 // this allocation. 699 HeapWord* new_top = new_obj + word_size; 700 701 // First, we need to zero the header of the space that we will be 702 // allocating. When we update top further down, some refinement 703 // threads might try to scan the region. By zeroing the header we 704 // ensure that any thread that will try to scan the region will 705 // come across the zero klass word and bail out. 706 // 707 // NOTE: It would not have been correct to have used 708 // CollectedHeap::fill_with_object() and make the space look like 709 // an int array. The thread that is doing the allocation will 710 // later update the object header to a potentially different array 711 // type and, for a very short period of time, the klass and length 712 // fields will be inconsistent. This could cause a refinement 713 // thread to calculate the object size incorrectly. 714 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 715 716 // We will set up the first region as "starts humongous". This 717 // will also update the BOT covering all the regions to reflect 718 // that there is a single object that starts at the bottom of the 719 // first region. 720 first_hr->set_startsHumongous(new_top, new_end); 721 722 // Then, if there are any, we will set up the "continues 723 // humongous" regions. 724 HeapRegion* hr = NULL; 725 for (uint i = first + 1; i < last; ++i) { 726 hr = region_at(i); 727 hr->set_continuesHumongous(first_hr); 728 } 729 // If we have "continues humongous" regions (hr != NULL), then the 730 // end of the last one should match new_end. 731 assert(hr == NULL || hr->end() == new_end, "sanity"); 732 733 // Up to this point no concurrent thread would have been able to 734 // do any scanning on any region in this series. All the top 735 // fields still point to bottom, so the intersection between 736 // [bottom,top] and [card_start,card_end] will be empty. Before we 737 // update the top fields, we'll do a storestore to make sure that 738 // no thread sees the update to top before the zeroing of the 739 // object header and the BOT initialization. 740 OrderAccess::storestore(); 741 742 // Now that the BOT and the object header have been initialized, 743 // we can update top of the "starts humongous" region. 744 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 745 "new_top should be in this region"); 746 first_hr->set_top(new_top); 747 if (_hr_printer.is_active()) { 748 HeapWord* bottom = first_hr->bottom(); 749 HeapWord* end = first_hr->orig_end(); 750 if ((first + 1) == last) { 751 // the series has a single humongous region 752 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 753 } else { 754 // the series has more than one humongous regions 755 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 756 } 757 } 758 759 // Now, we will update the top fields of the "continues humongous" 760 // regions. The reason we need to do this is that, otherwise, 761 // these regions would look empty and this will confuse parts of 762 // G1. For example, the code that looks for a consecutive number 763 // of empty regions will consider them empty and try to 764 // re-allocate them. We can extend is_empty() to also include 765 // !continuesHumongous(), but it is easier to just update the top 766 // fields here. The way we set top for all regions (i.e., top == 767 // end for all regions but the last one, top == new_top for the 768 // last one) is actually used when we will free up the humongous 769 // region in free_humongous_region(). 770 hr = NULL; 771 for (uint i = first + 1; i < last; ++i) { 772 hr = region_at(i); 773 if ((i + 1) == last) { 774 // last continues humongous region 775 assert(hr->bottom() < new_top && new_top <= hr->end(), 776 "new_top should fall on this region"); 777 hr->set_top(new_top); 778 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 779 } else { 780 // not last one 781 assert(new_top > hr->end(), "new_top should be above this region"); 782 hr->set_top(hr->end()); 783 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 784 } 785 } 786 // If we have continues humongous regions (hr != NULL), then the 787 // end of the last one should match new_end and its top should 788 // match new_top. 789 assert(hr == NULL || 790 (hr->end() == new_end && hr->top() == new_top), "sanity"); 791 792 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 793 _summary_bytes_used += first_hr->used(); 794 _humongous_set.add(first_hr); 795 796 return new_obj; 797 } 798 799 // If could fit into free regions w/o expansion, try. 800 // Otherwise, if can expand, do so. 801 // Otherwise, if using ex regions might help, try with ex given back. 802 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 803 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 804 805 verify_region_sets_optional(); 806 807 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 808 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 809 uint x_num = expansion_regions(); 810 uint fs = _hrs.free_suffix(); 811 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 812 if (first == G1_NULL_HRS_INDEX) { 813 // The only thing we can do now is attempt expansion. 814 if (fs + x_num >= num_regions) { 815 // If the number of regions we're trying to allocate for this 816 // object is at most the number of regions in the free suffix, 817 // then the call to humongous_obj_allocate_find_first() above 818 // should have succeeded and we wouldn't be here. 819 // 820 // We should only be trying to expand when the free suffix is 821 // not sufficient for the object _and_ we have some expansion 822 // room available. 823 assert(num_regions > fs, "earlier allocation should have succeeded"); 824 825 ergo_verbose1(ErgoHeapSizing, 826 "attempt heap expansion", 827 ergo_format_reason("humongous allocation request failed") 828 ergo_format_byte("allocation request"), 829 word_size * HeapWordSize); 830 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 831 // Even though the heap was expanded, it might not have 832 // reached the desired size. So, we cannot assume that the 833 // allocation will succeed. 834 first = humongous_obj_allocate_find_first(num_regions, word_size); 835 } 836 } 837 } 838 839 HeapWord* result = NULL; 840 if (first != G1_NULL_HRS_INDEX) { 841 result = 842 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 843 assert(result != NULL, "it should always return a valid result"); 844 845 // A successful humongous object allocation changes the used space 846 // information of the old generation so we need to recalculate the 847 // sizes and update the jstat counters here. 848 g1mm()->update_sizes(); 849 } 850 851 verify_region_sets_optional(); 852 853 return result; 854 } 855 856 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 857 assert_heap_not_locked_and_not_at_safepoint(); 858 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 859 860 unsigned int dummy_gc_count_before; 861 return attempt_allocation(word_size, &dummy_gc_count_before); 862 } 863 864 HeapWord* 865 G1CollectedHeap::mem_allocate(size_t word_size, 866 bool* gc_overhead_limit_was_exceeded) { 867 assert_heap_not_locked_and_not_at_safepoint(); 868 869 // Loop until the allocation is satisfied, or unsatisfied after GC. 870 for (int try_count = 1; /* we'll return */; try_count += 1) { 871 unsigned int gc_count_before; 872 873 HeapWord* result = NULL; 874 if (!isHumongous(word_size)) { 875 result = attempt_allocation(word_size, &gc_count_before); 876 } else { 877 result = attempt_allocation_humongous(word_size, &gc_count_before); 878 } 879 if (result != NULL) { 880 return result; 881 } 882 883 // Create the garbage collection operation... 884 VM_G1CollectForAllocation op(gc_count_before, word_size); 885 // ...and get the VM thread to execute it. 886 VMThread::execute(&op); 887 888 if (op.prologue_succeeded() && op.pause_succeeded()) { 889 // If the operation was successful we'll return the result even 890 // if it is NULL. If the allocation attempt failed immediately 891 // after a Full GC, it's unlikely we'll be able to allocate now. 892 HeapWord* result = op.result(); 893 if (result != NULL && !isHumongous(word_size)) { 894 // Allocations that take place on VM operations do not do any 895 // card dirtying and we have to do it here. We only have to do 896 // this for non-humongous allocations, though. 897 dirty_young_block(result, word_size); 898 } 899 return result; 900 } else { 901 assert(op.result() == NULL, 902 "the result should be NULL if the VM op did not succeed"); 903 } 904 905 // Give a warning if we seem to be looping forever. 906 if ((QueuedAllocationWarningCount > 0) && 907 (try_count % QueuedAllocationWarningCount == 0)) { 908 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 909 } 910 } 911 912 ShouldNotReachHere(); 913 return NULL; 914 } 915 916 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 917 unsigned int *gc_count_before_ret) { 918 // Make sure you read the note in attempt_allocation_humongous(). 919 920 assert_heap_not_locked_and_not_at_safepoint(); 921 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 922 "be called for humongous allocation requests"); 923 924 // We should only get here after the first-level allocation attempt 925 // (attempt_allocation()) failed to allocate. 926 927 // We will loop until a) we manage to successfully perform the 928 // allocation or b) we successfully schedule a collection which 929 // fails to perform the allocation. b) is the only case when we'll 930 // return NULL. 931 HeapWord* result = NULL; 932 for (int try_count = 1; /* we'll return */; try_count += 1) { 933 bool should_try_gc; 934 unsigned int gc_count_before; 935 936 { 937 MutexLockerEx x(Heap_lock); 938 939 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 940 false /* bot_updates */); 941 if (result != NULL) { 942 return result; 943 } 944 945 // If we reach here, attempt_allocation_locked() above failed to 946 // allocate a new region. So the mutator alloc region should be NULL. 947 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 948 949 if (GC_locker::is_active_and_needs_gc()) { 950 if (g1_policy()->can_expand_young_list()) { 951 // No need for an ergo verbose message here, 952 // can_expand_young_list() does this when it returns true. 953 result = _mutator_alloc_region.attempt_allocation_force(word_size, 954 false /* bot_updates */); 955 if (result != NULL) { 956 return result; 957 } 958 } 959 should_try_gc = false; 960 } else { 961 // The GCLocker may not be active but the GCLocker initiated 962 // GC may not yet have been performed (GCLocker::needs_gc() 963 // returns true). In this case we do not try this GC and 964 // wait until the GCLocker initiated GC is performed, and 965 // then retry the allocation. 966 if (GC_locker::needs_gc()) { 967 should_try_gc = false; 968 } else { 969 // Read the GC count while still holding the Heap_lock. 970 gc_count_before = total_collections(); 971 should_try_gc = true; 972 } 973 } 974 } 975 976 if (should_try_gc) { 977 bool succeeded; 978 result = do_collection_pause(word_size, gc_count_before, &succeeded); 979 if (result != NULL) { 980 assert(succeeded, "only way to get back a non-NULL result"); 981 return result; 982 } 983 984 if (succeeded) { 985 // If we get here we successfully scheduled a collection which 986 // failed to allocate. No point in trying to allocate 987 // further. We'll just return NULL. 988 MutexLockerEx x(Heap_lock); 989 *gc_count_before_ret = total_collections(); 990 return NULL; 991 } 992 } else { 993 // The GCLocker is either active or the GCLocker initiated 994 // GC has not yet been performed. Stall until it is and 995 // then retry the allocation. 996 GC_locker::stall_until_clear(); 997 } 998 999 // We can reach here if we were unsuccessful in scheduling a 1000 // collection (because another thread beat us to it) or if we were 1001 // stalled due to the GC locker. In either can we should retry the 1002 // allocation attempt in case another thread successfully 1003 // performed a collection and reclaimed enough space. We do the 1004 // first attempt (without holding the Heap_lock) here and the 1005 // follow-on attempt will be at the start of the next loop 1006 // iteration (after taking the Heap_lock). 1007 result = _mutator_alloc_region.attempt_allocation(word_size, 1008 false /* bot_updates */); 1009 if (result != NULL) { 1010 return result; 1011 } 1012 1013 // Give a warning if we seem to be looping forever. 1014 if ((QueuedAllocationWarningCount > 0) && 1015 (try_count % QueuedAllocationWarningCount == 0)) { 1016 warning("G1CollectedHeap::attempt_allocation_slow() " 1017 "retries %d times", try_count); 1018 } 1019 } 1020 1021 ShouldNotReachHere(); 1022 return NULL; 1023 } 1024 1025 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1026 unsigned int * gc_count_before_ret) { 1027 // The structure of this method has a lot of similarities to 1028 // attempt_allocation_slow(). The reason these two were not merged 1029 // into a single one is that such a method would require several "if 1030 // allocation is not humongous do this, otherwise do that" 1031 // conditional paths which would obscure its flow. In fact, an early 1032 // version of this code did use a unified method which was harder to 1033 // follow and, as a result, it had subtle bugs that were hard to 1034 // track down. So keeping these two methods separate allows each to 1035 // be more readable. It will be good to keep these two in sync as 1036 // much as possible. 1037 1038 assert_heap_not_locked_and_not_at_safepoint(); 1039 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1040 "should only be called for humongous allocations"); 1041 1042 // Humongous objects can exhaust the heap quickly, so we should check if we 1043 // need to start a marking cycle at each humongous object allocation. We do 1044 // the check before we do the actual allocation. The reason for doing it 1045 // before the allocation is that we avoid having to keep track of the newly 1046 // allocated memory while we do a GC. 1047 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1048 word_size)) { 1049 collect(GCCause::_g1_humongous_allocation); 1050 } 1051 1052 // We will loop until a) we manage to successfully perform the 1053 // allocation or b) we successfully schedule a collection which 1054 // fails to perform the allocation. b) is the only case when we'll 1055 // return NULL. 1056 HeapWord* result = NULL; 1057 for (int try_count = 1; /* we'll return */; try_count += 1) { 1058 bool should_try_gc; 1059 unsigned int gc_count_before; 1060 1061 { 1062 MutexLockerEx x(Heap_lock); 1063 1064 // Given that humongous objects are not allocated in young 1065 // regions, we'll first try to do the allocation without doing a 1066 // collection hoping that there's enough space in the heap. 1067 result = humongous_obj_allocate(word_size); 1068 if (result != NULL) { 1069 return result; 1070 } 1071 1072 if (GC_locker::is_active_and_needs_gc()) { 1073 should_try_gc = false; 1074 } else { 1075 // The GCLocker may not be active but the GCLocker initiated 1076 // GC may not yet have been performed (GCLocker::needs_gc() 1077 // returns true). In this case we do not try this GC and 1078 // wait until the GCLocker initiated GC is performed, and 1079 // then retry the allocation. 1080 if (GC_locker::needs_gc()) { 1081 should_try_gc = false; 1082 } else { 1083 // Read the GC count while still holding the Heap_lock. 1084 gc_count_before = total_collections(); 1085 should_try_gc = true; 1086 } 1087 } 1088 } 1089 1090 if (should_try_gc) { 1091 // If we failed to allocate the humongous object, we should try to 1092 // do a collection pause (if we're allowed) in case it reclaims 1093 // enough space for the allocation to succeed after the pause. 1094 1095 bool succeeded; 1096 result = do_collection_pause(word_size, gc_count_before, &succeeded); 1097 if (result != NULL) { 1098 assert(succeeded, "only way to get back a non-NULL result"); 1099 return result; 1100 } 1101 1102 if (succeeded) { 1103 // If we get here we successfully scheduled a collection which 1104 // failed to allocate. No point in trying to allocate 1105 // further. We'll just return NULL. 1106 MutexLockerEx x(Heap_lock); 1107 *gc_count_before_ret = total_collections(); 1108 return NULL; 1109 } 1110 } else { 1111 // The GCLocker is either active or the GCLocker initiated 1112 // GC has not yet been performed. Stall until it is and 1113 // then retry the allocation. 1114 GC_locker::stall_until_clear(); 1115 } 1116 1117 // We can reach here if we were unsuccessful in scheduling a 1118 // collection (because another thread beat us to it) or if we were 1119 // stalled due to the GC locker. In either can we should retry the 1120 // allocation attempt in case another thread successfully 1121 // performed a collection and reclaimed enough space. Give a 1122 // warning if we seem to be looping forever. 1123 1124 if ((QueuedAllocationWarningCount > 0) && 1125 (try_count % QueuedAllocationWarningCount == 0)) { 1126 warning("G1CollectedHeap::attempt_allocation_humongous() " 1127 "retries %d times", try_count); 1128 } 1129 } 1130 1131 ShouldNotReachHere(); 1132 return NULL; 1133 } 1134 1135 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1136 bool expect_null_mutator_alloc_region) { 1137 assert_at_safepoint(true /* should_be_vm_thread */); 1138 assert(_mutator_alloc_region.get() == NULL || 1139 !expect_null_mutator_alloc_region, 1140 "the current alloc region was unexpectedly found to be non-NULL"); 1141 1142 if (!isHumongous(word_size)) { 1143 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1144 false /* bot_updates */); 1145 } else { 1146 HeapWord* result = humongous_obj_allocate(word_size); 1147 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1148 g1_policy()->set_initiate_conc_mark_if_possible(); 1149 } 1150 return result; 1151 } 1152 1153 ShouldNotReachHere(); 1154 } 1155 1156 class PostMCRemSetClearClosure: public HeapRegionClosure { 1157 G1CollectedHeap* _g1h; 1158 ModRefBarrierSet* _mr_bs; 1159 public: 1160 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1161 _g1h(g1h), _mr_bs(mr_bs) { } 1162 bool doHeapRegion(HeapRegion* r) { 1163 if (r->continuesHumongous()) { 1164 return false; 1165 } 1166 _g1h->reset_gc_time_stamps(r); 1167 HeapRegionRemSet* hrrs = r->rem_set(); 1168 if (hrrs != NULL) hrrs->clear(); 1169 // You might think here that we could clear just the cards 1170 // corresponding to the used region. But no: if we leave a dirty card 1171 // in a region we might allocate into, then it would prevent that card 1172 // from being enqueued, and cause it to be missed. 1173 // Re: the performance cost: we shouldn't be doing full GC anyway! 1174 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1175 return false; 1176 } 1177 }; 1178 1179 void G1CollectedHeap::clear_rsets_post_compaction() { 1180 PostMCRemSetClearClosure rs_clear(this, mr_bs()); 1181 heap_region_iterate(&rs_clear); 1182 } 1183 1184 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1185 G1CollectedHeap* _g1h; 1186 UpdateRSOopClosure _cl; 1187 int _worker_i; 1188 public: 1189 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1190 _cl(g1->g1_rem_set(), worker_i), 1191 _worker_i(worker_i), 1192 _g1h(g1) 1193 { } 1194 1195 bool doHeapRegion(HeapRegion* r) { 1196 if (!r->continuesHumongous()) { 1197 _cl.set_from(r); 1198 r->oop_iterate(&_cl); 1199 } 1200 return false; 1201 } 1202 }; 1203 1204 class ParRebuildRSTask: public AbstractGangTask { 1205 G1CollectedHeap* _g1; 1206 public: 1207 ParRebuildRSTask(G1CollectedHeap* g1) 1208 : AbstractGangTask("ParRebuildRSTask"), 1209 _g1(g1) 1210 { } 1211 1212 void work(uint worker_id) { 1213 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1214 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1215 _g1->workers()->active_workers(), 1216 HeapRegion::RebuildRSClaimValue); 1217 } 1218 }; 1219 1220 class PostCompactionPrinterClosure: public HeapRegionClosure { 1221 private: 1222 G1HRPrinter* _hr_printer; 1223 public: 1224 bool doHeapRegion(HeapRegion* hr) { 1225 assert(!hr->is_young(), "not expecting to find young regions"); 1226 // We only generate output for non-empty regions. 1227 if (!hr->is_empty()) { 1228 if (!hr->isHumongous()) { 1229 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1230 } else if (hr->startsHumongous()) { 1231 if (hr->region_num() == 1) { 1232 // single humongous region 1233 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1234 } else { 1235 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1236 } 1237 } else { 1238 assert(hr->continuesHumongous(), "only way to get here"); 1239 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1240 } 1241 } 1242 return false; 1243 } 1244 1245 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1246 : _hr_printer(hr_printer) { } 1247 }; 1248 1249 void G1CollectedHeap::print_hrs_post_compaction() { 1250 PostCompactionPrinterClosure cl(hr_printer()); 1251 heap_region_iterate(&cl); 1252 } 1253 1254 double G1CollectedHeap::verify(bool guard, const char* msg) { 1255 double verify_time_ms = 0.0; 1256 1257 if (guard && total_collections() >= VerifyGCStartAt) { 1258 double verify_start = os::elapsedTime(); 1259 HandleMark hm; // Discard invalid handles created during verification 1260 gclog_or_tty->print(msg); 1261 prepare_for_verify(); 1262 Universe::verify(false /* silent */, VerifyOption_G1UsePrevMarking); 1263 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 1264 } 1265 1266 return verify_time_ms; 1267 } 1268 1269 void G1CollectedHeap::verify_before_gc() { 1270 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 1271 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 1272 } 1273 1274 void G1CollectedHeap::verify_after_gc() { 1275 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 1276 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 1277 } 1278 1279 bool G1CollectedHeap::do_collection(bool explicit_gc, 1280 bool clear_all_soft_refs, 1281 size_t word_size) { 1282 assert_at_safepoint(true /* should_be_vm_thread */); 1283 1284 if (GC_locker::check_active_before_gc()) { 1285 return false; 1286 } 1287 1288 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1289 gc_timer->register_gc_start(os::elapsed_counter()); 1290 1291 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1292 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1293 1294 SvcGCMarker sgcm(SvcGCMarker::FULL); 1295 ResourceMark rm; 1296 1297 print_heap_before_gc(); 1298 trace_heap_before_gc(gc_tracer); 1299 1300 HRSPhaseSetter x(HRSPhaseFullGC); 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 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1314 1315 { 1316 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1317 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1318 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1319 1320 double start = os::elapsedTime(); 1321 g1_policy()->record_full_collection_start(); 1322 1323 // Note: When we have a more flexible GC logging framework that 1324 // allows us to add optional attributes to a GC log record we 1325 // could consider timing and reporting how long we wait in the 1326 // following two methods. 1327 wait_while_free_regions_coming(); 1328 // If we start the compaction before the CM threads finish 1329 // scanning the root regions we might trip them over as we'll 1330 // be moving objects / updating references. So let's wait until 1331 // they are done. By telling them to abort, they should complete 1332 // early. 1333 _cm->root_regions()->abort(); 1334 _cm->root_regions()->wait_until_scan_finished(); 1335 append_secondary_free_list_if_not_empty_with_lock(); 1336 1337 gc_prologue(true); 1338 increment_total_collections(true /* full gc */); 1339 increment_old_marking_cycles_started(); 1340 1341 assert(used() == recalculate_used(), "Should be equal"); 1342 1343 verify_before_gc(); 1344 1345 pre_full_gc_dump(gc_timer); 1346 1347 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1348 1349 // Disable discovery and empty the discovered lists 1350 // for the CM ref processor. 1351 ref_processor_cm()->disable_discovery(); 1352 ref_processor_cm()->abandon_partial_discovery(); 1353 ref_processor_cm()->verify_no_references_recorded(); 1354 1355 // Abandon current iterations of concurrent marking and concurrent 1356 // refinement, if any are in progress. We have to do this before 1357 // wait_until_scan_finished() below. 1358 concurrent_mark()->abort(); 1359 1360 // Make sure we'll choose a new allocation region afterwards. 1361 release_mutator_alloc_region(); 1362 abandon_gc_alloc_regions(); 1363 g1_rem_set()->cleanupHRRS(); 1364 1365 // We should call this after we retire any currently active alloc 1366 // regions so that all the ALLOC / RETIRE events are generated 1367 // before the start GC event. 1368 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1369 1370 // We may have added regions to the current incremental collection 1371 // set between the last GC or pause and now. We need to clear the 1372 // incremental collection set and then start rebuilding it afresh 1373 // after this full GC. 1374 abandon_collection_set(g1_policy()->inc_cset_head()); 1375 g1_policy()->clear_incremental_cset(); 1376 g1_policy()->stop_incremental_cset_building(); 1377 1378 tear_down_region_sets(false /* free_list_only */); 1379 g1_policy()->set_gcs_are_young(true); 1380 1381 // See the comments in g1CollectedHeap.hpp and 1382 // G1CollectedHeap::ref_processing_init() about 1383 // how reference processing currently works in G1. 1384 1385 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1386 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1387 1388 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1389 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1390 1391 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1392 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1393 1394 // Do collection work 1395 { 1396 HandleMark hm; // Discard invalid handles created during gc 1397 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1398 } 1399 1400 assert(free_regions() == 0, "we should not have added any free regions"); 1401 rebuild_region_sets(false /* free_list_only */); 1402 1403 // Enqueue any discovered reference objects that have 1404 // not been removed from the discovered lists. 1405 ref_processor_stw()->enqueue_discovered_references(); 1406 1407 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1408 1409 MemoryService::track_memory_usage(); 1410 1411 verify_after_gc(); 1412 1413 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1414 ref_processor_stw()->verify_no_references_recorded(); 1415 1416 // Note: since we've just done a full GC, concurrent 1417 // marking is no longer active. Therefore we need not 1418 // re-enable reference discovery for the CM ref processor. 1419 // That will be done at the start of the next marking cycle. 1420 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1421 ref_processor_cm()->verify_no_references_recorded(); 1422 1423 reset_gc_time_stamp(); 1424 // Since everything potentially moved, we will clear all remembered 1425 // sets, and clear all cards. Later we will rebuild remembered 1426 // sets. We will also reset the GC time stamps of the regions. 1427 clear_rsets_post_compaction(); 1428 check_gc_time_stamps(); 1429 1430 // Resize the heap if necessary. 1431 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1432 1433 if (_hr_printer.is_active()) { 1434 // We should do this after we potentially resize the heap so 1435 // that all the COMMIT / UNCOMMIT events are generated before 1436 // the end GC event. 1437 1438 print_hrs_post_compaction(); 1439 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1440 } 1441 1442 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1443 if (hot_card_cache->use_cache()) { 1444 hot_card_cache->reset_card_counts(); 1445 hot_card_cache->reset_hot_cache(); 1446 } 1447 1448 // Rebuild remembered sets of all regions. 1449 if (G1CollectedHeap::use_parallel_gc_threads()) { 1450 uint n_workers = 1451 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1452 workers()->active_workers(), 1453 Threads::number_of_non_daemon_threads()); 1454 assert(UseDynamicNumberOfGCThreads || 1455 n_workers == workers()->total_workers(), 1456 "If not dynamic should be using all the workers"); 1457 workers()->set_active_workers(n_workers); 1458 // Set parallel threads in the heap (_n_par_threads) only 1459 // before a parallel phase and always reset it to 0 after 1460 // the phase so that the number of parallel threads does 1461 // no get carried forward to a serial phase where there 1462 // may be code that is "possibly_parallel". 1463 set_par_threads(n_workers); 1464 1465 ParRebuildRSTask rebuild_rs_task(this); 1466 assert(check_heap_region_claim_values( 1467 HeapRegion::InitialClaimValue), "sanity check"); 1468 assert(UseDynamicNumberOfGCThreads || 1469 workers()->active_workers() == workers()->total_workers(), 1470 "Unless dynamic should use total workers"); 1471 // Use the most recent number of active workers 1472 assert(workers()->active_workers() > 0, 1473 "Active workers not properly set"); 1474 set_par_threads(workers()->active_workers()); 1475 workers()->run_task(&rebuild_rs_task); 1476 set_par_threads(0); 1477 assert(check_heap_region_claim_values( 1478 HeapRegion::RebuildRSClaimValue), "sanity check"); 1479 reset_heap_region_claim_values(); 1480 } else { 1481 RebuildRSOutOfRegionClosure rebuild_rs(this); 1482 heap_region_iterate(&rebuild_rs); 1483 } 1484 1485 if (true) { // FIXME 1486 // Ask the permanent generation to adjust size for full collections 1487 perm()->compute_new_size(); 1488 } 1489 1490 #ifdef TRACESPINNING 1491 ParallelTaskTerminator::print_termination_counts(); 1492 #endif 1493 1494 // Discard all rset updates 1495 JavaThread::dirty_card_queue_set().abandon_logs(); 1496 assert(!G1DeferredRSUpdate 1497 || (G1DeferredRSUpdate && 1498 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1499 1500 _young_list->reset_sampled_info(); 1501 // At this point there should be no regions in the 1502 // entire heap tagged as young. 1503 assert(check_young_list_empty(true /* check_heap */), 1504 "young list should be empty at this point"); 1505 1506 // Update the number of full collections that have been completed. 1507 increment_old_marking_cycles_completed(false /* concurrent */); 1508 1509 _hrs.verify_optional(); 1510 verify_region_sets_optional(); 1511 1512 // Start a new incremental collection set for the next pause 1513 assert(g1_policy()->collection_set() == NULL, "must be"); 1514 g1_policy()->start_incremental_cset_building(); 1515 1516 // Clear the _cset_fast_test bitmap in anticipation of adding 1517 // regions to the incremental collection set for the next 1518 // evacuation pause. 1519 clear_cset_fast_test(); 1520 1521 init_mutator_alloc_region(); 1522 1523 double end = os::elapsedTime(); 1524 g1_policy()->record_full_collection_end(); 1525 1526 if (G1Log::fine()) { 1527 g1_policy()->print_heap_transition(); 1528 } 1529 1530 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1531 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1532 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1533 // before any GC notifications are raised. 1534 g1mm()->update_sizes(); 1535 1536 gc_epilogue(true); 1537 } 1538 1539 if (G1Log::finer()) { 1540 g1_policy()->print_detailed_heap_transition(); 1541 } 1542 1543 print_heap_after_gc(); 1544 trace_heap_after_gc(gc_tracer); 1545 1546 post_full_gc_dump(gc_timer); 1547 } 1548 1549 gc_timer->register_gc_end(os::elapsed_counter()); 1550 1551 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1552 1553 return true; 1554 } 1555 1556 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1557 // do_collection() will return whether it succeeded in performing 1558 // the GC. Currently, there is no facility on the 1559 // do_full_collection() API to notify the caller than the collection 1560 // did not succeed (e.g., because it was locked out by the GC 1561 // locker). So, right now, we'll ignore the return value. 1562 bool dummy = do_collection(true, /* explicit_gc */ 1563 clear_all_soft_refs, 1564 0 /* word_size */); 1565 } 1566 1567 // This code is mostly copied from TenuredGeneration. 1568 void 1569 G1CollectedHeap:: 1570 resize_if_necessary_after_full_collection(size_t word_size) { 1571 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check"); 1572 1573 // Include the current allocation, if any, and bytes that will be 1574 // pre-allocated to support collections, as "used". 1575 const size_t used_after_gc = used(); 1576 const size_t capacity_after_gc = capacity(); 1577 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1578 1579 // This is enforced in arguments.cpp. 1580 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1581 "otherwise the code below doesn't make sense"); 1582 1583 // We don't have floating point command-line arguments 1584 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1585 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1586 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1587 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1588 1589 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1590 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1591 1592 // We have to be careful here as these two calculations can overflow 1593 // 32-bit size_t's. 1594 double used_after_gc_d = (double) used_after_gc; 1595 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1596 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1597 1598 // Let's make sure that they are both under the max heap size, which 1599 // by default will make them fit into a size_t. 1600 double desired_capacity_upper_bound = (double) max_heap_size; 1601 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1602 desired_capacity_upper_bound); 1603 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1604 desired_capacity_upper_bound); 1605 1606 // We can now safely turn them into size_t's. 1607 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1608 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1609 1610 // This assert only makes sense here, before we adjust them 1611 // with respect to the min and max heap size. 1612 assert(minimum_desired_capacity <= maximum_desired_capacity, 1613 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1614 "maximum_desired_capacity = "SIZE_FORMAT, 1615 minimum_desired_capacity, maximum_desired_capacity)); 1616 1617 // Should not be greater than the heap max size. No need to adjust 1618 // it with respect to the heap min size as it's a lower bound (i.e., 1619 // we'll try to make the capacity larger than it, not smaller). 1620 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1621 // Should not be less than the heap min size. No need to adjust it 1622 // with respect to the heap max size as it's an upper bound (i.e., 1623 // we'll try to make the capacity smaller than it, not greater). 1624 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1625 1626 if (capacity_after_gc < minimum_desired_capacity) { 1627 // Don't expand unless it's significant 1628 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1629 ergo_verbose4(ErgoHeapSizing, 1630 "attempt heap expansion", 1631 ergo_format_reason("capacity lower than " 1632 "min desired capacity after Full GC") 1633 ergo_format_byte("capacity") 1634 ergo_format_byte("occupancy") 1635 ergo_format_byte_perc("min desired capacity"), 1636 capacity_after_gc, used_after_gc, 1637 minimum_desired_capacity, (double) MinHeapFreeRatio); 1638 expand(expand_bytes); 1639 1640 // No expansion, now see if we want to shrink 1641 } else if (capacity_after_gc > maximum_desired_capacity) { 1642 // Capacity too large, compute shrinking size 1643 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1644 ergo_verbose4(ErgoHeapSizing, 1645 "attempt heap shrinking", 1646 ergo_format_reason("capacity higher than " 1647 "max desired capacity after Full GC") 1648 ergo_format_byte("capacity") 1649 ergo_format_byte("occupancy") 1650 ergo_format_byte_perc("max desired capacity"), 1651 capacity_after_gc, used_after_gc, 1652 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1653 shrink(shrink_bytes); 1654 } 1655 } 1656 1657 1658 HeapWord* 1659 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1660 bool* succeeded) { 1661 assert_at_safepoint(true /* should_be_vm_thread */); 1662 1663 *succeeded = true; 1664 // Let's attempt the allocation first. 1665 HeapWord* result = 1666 attempt_allocation_at_safepoint(word_size, 1667 false /* expect_null_mutator_alloc_region */); 1668 if (result != NULL) { 1669 assert(*succeeded, "sanity"); 1670 return result; 1671 } 1672 1673 // In a G1 heap, we're supposed to keep allocation from failing by 1674 // incremental pauses. Therefore, at least for now, we'll favor 1675 // expansion over collection. (This might change in the future if we can 1676 // do something smarter than full collection to satisfy a failed alloc.) 1677 result = expand_and_allocate(word_size); 1678 if (result != NULL) { 1679 assert(*succeeded, "sanity"); 1680 return result; 1681 } 1682 1683 // Expansion didn't work, we'll try to do a Full GC. 1684 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1685 false, /* clear_all_soft_refs */ 1686 word_size); 1687 if (!gc_succeeded) { 1688 *succeeded = false; 1689 return NULL; 1690 } 1691 1692 // Retry the allocation 1693 result = attempt_allocation_at_safepoint(word_size, 1694 true /* expect_null_mutator_alloc_region */); 1695 if (result != NULL) { 1696 assert(*succeeded, "sanity"); 1697 return result; 1698 } 1699 1700 // Then, try a Full GC that will collect all soft references. 1701 gc_succeeded = do_collection(false, /* explicit_gc */ 1702 true, /* clear_all_soft_refs */ 1703 word_size); 1704 if (!gc_succeeded) { 1705 *succeeded = false; 1706 return NULL; 1707 } 1708 1709 // Retry the allocation once more 1710 result = attempt_allocation_at_safepoint(word_size, 1711 true /* expect_null_mutator_alloc_region */); 1712 if (result != NULL) { 1713 assert(*succeeded, "sanity"); 1714 return result; 1715 } 1716 1717 assert(!collector_policy()->should_clear_all_soft_refs(), 1718 "Flag should have been handled and cleared prior to this point"); 1719 1720 // What else? We might try synchronous finalization later. If the total 1721 // space available is large enough for the allocation, then a more 1722 // complete compaction phase than we've tried so far might be 1723 // appropriate. 1724 assert(*succeeded, "sanity"); 1725 return NULL; 1726 } 1727 1728 // Attempting to expand the heap sufficiently 1729 // to support an allocation of the given "word_size". If 1730 // successful, perform the allocation and return the address of the 1731 // allocated block, or else "NULL". 1732 1733 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1734 assert_at_safepoint(true /* should_be_vm_thread */); 1735 1736 verify_region_sets_optional(); 1737 1738 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1739 ergo_verbose1(ErgoHeapSizing, 1740 "attempt heap expansion", 1741 ergo_format_reason("allocation request failed") 1742 ergo_format_byte("allocation request"), 1743 word_size * HeapWordSize); 1744 if (expand(expand_bytes)) { 1745 _hrs.verify_optional(); 1746 verify_region_sets_optional(); 1747 return attempt_allocation_at_safepoint(word_size, 1748 false /* expect_null_mutator_alloc_region */); 1749 } 1750 return NULL; 1751 } 1752 1753 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1754 HeapWord* new_end) { 1755 assert(old_end != new_end, "don't call this otherwise"); 1756 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1757 1758 // Update the committed mem region. 1759 _g1_committed.set_end(new_end); 1760 // Tell the card table about the update. 1761 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1762 // Tell the BOT about the update. 1763 _bot_shared->resize(_g1_committed.word_size()); 1764 // Tell the hot card cache about the update 1765 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1766 } 1767 1768 bool G1CollectedHeap::expand(size_t expand_bytes) { 1769 size_t old_mem_size = _g1_storage.committed_size(); 1770 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1771 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1772 HeapRegion::GrainBytes); 1773 ergo_verbose2(ErgoHeapSizing, 1774 "expand the heap", 1775 ergo_format_byte("requested expansion amount") 1776 ergo_format_byte("attempted expansion amount"), 1777 expand_bytes, aligned_expand_bytes); 1778 1779 // First commit the memory. 1780 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1781 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1782 if (successful) { 1783 // Then propagate this update to the necessary data structures. 1784 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1785 update_committed_space(old_end, new_end); 1786 1787 FreeRegionList expansion_list("Local Expansion List"); 1788 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1789 assert(mr.start() == old_end, "post-condition"); 1790 // mr might be a smaller region than what was requested if 1791 // expand_by() was unable to allocate the HeapRegion instances 1792 assert(mr.end() <= new_end, "post-condition"); 1793 1794 size_t actual_expand_bytes = mr.byte_size(); 1795 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1796 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1797 "post-condition"); 1798 if (actual_expand_bytes < aligned_expand_bytes) { 1799 // We could not expand _hrs to the desired size. In this case we 1800 // need to shrink the committed space accordingly. 1801 assert(mr.end() < new_end, "invariant"); 1802 1803 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1804 // First uncommit the memory. 1805 _g1_storage.shrink_by(diff_bytes); 1806 // Then propagate this update to the necessary data structures. 1807 update_committed_space(new_end, mr.end()); 1808 } 1809 _free_list.add_as_tail(&expansion_list); 1810 1811 if (_hr_printer.is_active()) { 1812 HeapWord* curr = mr.start(); 1813 while (curr < mr.end()) { 1814 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1815 _hr_printer.commit(curr, curr_end); 1816 curr = curr_end; 1817 } 1818 assert(curr == mr.end(), "post-condition"); 1819 } 1820 g1_policy()->record_new_heap_size(n_regions()); 1821 } else { 1822 ergo_verbose0(ErgoHeapSizing, 1823 "did not expand the heap", 1824 ergo_format_reason("heap expansion operation failed")); 1825 // The expansion of the virtual storage space was unsuccessful. 1826 // Let's see if it was because we ran out of swap. 1827 if (G1ExitOnExpansionFailure && 1828 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1829 // We had head room... 1830 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion"); 1831 } 1832 } 1833 return successful; 1834 } 1835 1836 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1837 size_t old_mem_size = _g1_storage.committed_size(); 1838 size_t aligned_shrink_bytes = 1839 ReservedSpace::page_align_size_down(shrink_bytes); 1840 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1841 HeapRegion::GrainBytes); 1842 uint num_regions_deleted = 0; 1843 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted); 1844 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1845 assert(mr.end() == old_end, "post-condition"); 1846 1847 ergo_verbose3(ErgoHeapSizing, 1848 "shrink the heap", 1849 ergo_format_byte("requested shrinking amount") 1850 ergo_format_byte("aligned shrinking amount") 1851 ergo_format_byte("attempted shrinking amount"), 1852 shrink_bytes, aligned_shrink_bytes, mr.byte_size()); 1853 if (mr.byte_size() > 0) { 1854 if (_hr_printer.is_active()) { 1855 HeapWord* curr = mr.end(); 1856 while (curr > mr.start()) { 1857 HeapWord* curr_end = curr; 1858 curr -= HeapRegion::GrainWords; 1859 _hr_printer.uncommit(curr, curr_end); 1860 } 1861 assert(curr == mr.start(), "post-condition"); 1862 } 1863 1864 _g1_storage.shrink_by(mr.byte_size()); 1865 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1866 assert(mr.start() == new_end, "post-condition"); 1867 1868 _expansion_regions += num_regions_deleted; 1869 update_committed_space(old_end, new_end); 1870 HeapRegionRemSet::shrink_heap(n_regions()); 1871 g1_policy()->record_new_heap_size(n_regions()); 1872 } else { 1873 ergo_verbose0(ErgoHeapSizing, 1874 "did not shrink the heap", 1875 ergo_format_reason("heap shrinking operation failed")); 1876 } 1877 } 1878 1879 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1880 verify_region_sets_optional(); 1881 1882 // We should only reach here at the end of a Full GC which means we 1883 // should not not be holding to any GC alloc regions. The method 1884 // below will make sure of that and do any remaining clean up. 1885 abandon_gc_alloc_regions(); 1886 1887 // Instead of tearing down / rebuilding the free lists here, we 1888 // could instead use the remove_all_pending() method on free_list to 1889 // remove only the ones that we need to remove. 1890 tear_down_region_sets(true /* free_list_only */); 1891 shrink_helper(shrink_bytes); 1892 rebuild_region_sets(true /* free_list_only */); 1893 1894 _hrs.verify_optional(); 1895 verify_region_sets_optional(); 1896 } 1897 1898 // Public methods. 1899 1900 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1901 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1902 #endif // _MSC_VER 1903 1904 1905 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1906 SharedHeap(policy_), 1907 _g1_policy(policy_), 1908 _dirty_card_queue_set(false), 1909 _into_cset_dirty_card_queue_set(false), 1910 _is_alive_closure_cm(this), 1911 _is_alive_closure_stw(this), 1912 _ref_processor_cm(NULL), 1913 _ref_processor_stw(NULL), 1914 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1915 _bot_shared(NULL), 1916 _evac_failure_scan_stack(NULL), 1917 _mark_in_progress(false), 1918 _cg1r(NULL), _summary_bytes_used(0), 1919 _g1mm(NULL), 1920 _refine_cte_cl(NULL), 1921 _full_collection(false), 1922 _free_list("Master Free List"), 1923 _secondary_free_list("Secondary Free List"), 1924 _old_set("Old Set"), 1925 _humongous_set("Master Humongous Set"), 1926 _free_regions_coming(false), 1927 _young_list(new YoungList(this)), 1928 _gc_time_stamp(0), 1929 _retained_old_gc_alloc_region(NULL), 1930 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1931 _old_plab_stats(OldPLABSize, PLABWeight), 1932 _expand_heap_after_alloc_failure(true), 1933 _surviving_young_words(NULL), 1934 _old_marking_cycles_started(0), 1935 _old_marking_cycles_completed(0), 1936 _concurrent_cycle_started(false), 1937 _in_cset_fast_test(NULL), 1938 _in_cset_fast_test_base(NULL), 1939 _dirty_cards_region_list(NULL), 1940 _worker_cset_start_region(NULL), 1941 _worker_cset_start_region_time_stamp(NULL), 1942 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1943 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1944 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1945 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1946 1947 _g1h = this; 1948 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1949 vm_exit_during_initialization("Failed necessary allocation."); 1950 } 1951 1952 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1953 1954 int n_queues = MAX2((int)ParallelGCThreads, 1); 1955 _task_queues = new RefToScanQueueSet(n_queues); 1956 1957 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1958 assert(n_rem_sets > 0, "Invariant."); 1959 1960 HeapRegionRemSetIterator** iter_arr = NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues, mtGC); 1961 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1962 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1963 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1964 1965 for (int i = 0; i < n_queues; i++) { 1966 RefToScanQueue* q = new RefToScanQueue(); 1967 q->initialize(); 1968 _task_queues->register_queue(i, q); 1969 iter_arr[i] = new HeapRegionRemSetIterator(); 1970 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1971 } 1972 _rem_set_iterator = iter_arr; 1973 1974 clear_cset_start_regions(); 1975 1976 // Initialize the G1EvacuationFailureALot counters and flags. 1977 NOT_PRODUCT(reset_evacuation_should_fail();) 1978 1979 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1980 } 1981 1982 jint G1CollectedHeap::initialize() { 1983 CollectedHeap::pre_initialize(); 1984 os::enable_vtime(); 1985 1986 G1Log::init(); 1987 1988 // Necessary to satisfy locking discipline assertions. 1989 1990 MutexLocker x(Heap_lock); 1991 1992 // We have to initialize the printer before committing the heap, as 1993 // it will be used then. 1994 _hr_printer.set_active(G1PrintHeapRegions); 1995 1996 // While there are no constraints in the GC code that HeapWordSize 1997 // be any particular value, there are multiple other areas in the 1998 // system which believe this to be true (e.g. oop->object_size in some 1999 // cases incorrectly returns the size in wordSize units rather than 2000 // HeapWordSize). 2001 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2002 2003 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2004 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2005 size_t heap_alignment = collector_policy()->max_alignment(); 2006 2007 // Ensure that the sizes are properly aligned. 2008 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2009 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2010 2011 _cg1r = new ConcurrentG1Refine(this); 2012 2013 // Reserve the maximum. 2014 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation(); 2015 // Includes the perm-gen. 2016 2017 // When compressed oops are enabled, the preferred heap base 2018 // is calculated by subtracting the requested size from the 2019 // 32Gb boundary and using the result as the base address for 2020 // heap reservation. If the requested size is not aligned to 2021 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2022 // into the ReservedHeapSpace constructor) then the actual 2023 // base of the reserved heap may end up differing from the 2024 // address that was requested (i.e. the preferred heap base). 2025 // If this happens then we could end up using a non-optimal 2026 // compressed oops mode. 2027 2028 // Since max_byte_size is aligned to the size of a heap region (checked 2029 // above), we also need to align the perm gen size as it might not be. 2030 size_t total_reserved = 0; 2031 2032 total_reserved = add_and_check_overflow(total_reserved, max_byte_size); 2033 size_t pg_max_size = (size_t) align_size_up(pgs->max_size(), heap_alignment); 2034 total_reserved = add_and_check_overflow(total_reserved, pg_max_size); 2035 2036 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm"); 2037 2038 char* addr = Universe::preferred_heap_base(total_reserved, heap_alignment, Universe::UnscaledNarrowOop); 2039 2040 ReservedHeapSpace heap_rs(total_reserved, heap_alignment, 2041 UseLargePages, addr); 2042 2043 if (UseCompressedOops) { 2044 if (addr != NULL && !heap_rs.is_reserved()) { 2045 // Failed to reserve at specified address - the requested memory 2046 // region is taken already, for example, by 'java' launcher. 2047 // Try again to reserver heap higher. 2048 addr = Universe::preferred_heap_base(total_reserved, heap_alignment, Universe::ZeroBasedNarrowOop); 2049 2050 ReservedHeapSpace heap_rs0(total_reserved, heap_alignment, 2051 UseLargePages, addr); 2052 2053 if (addr != NULL && !heap_rs0.is_reserved()) { 2054 // Failed to reserve at specified address again - give up. 2055 addr = Universe::preferred_heap_base(total_reserved, heap_alignment, Universe::HeapBasedNarrowOop); 2056 assert(addr == NULL, ""); 2057 2058 ReservedHeapSpace heap_rs1(total_reserved, heap_alignment, 2059 UseLargePages, addr); 2060 heap_rs = heap_rs1; 2061 } else { 2062 heap_rs = heap_rs0; 2063 } 2064 } 2065 } 2066 2067 if (!heap_rs.is_reserved()) { 2068 vm_exit_during_initialization("Could not reserve enough space for object heap"); 2069 return JNI_ENOMEM; 2070 } 2071 2072 // It is important to do this in a way such that concurrent readers can't 2073 // temporarily think something is in the heap. (I've actually seen this 2074 // happen in asserts: DLD.) 2075 _reserved.set_word_size(0); 2076 _reserved.set_start((HeapWord*)heap_rs.base()); 2077 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2078 2079 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2080 2081 // Create the gen rem set (and barrier set) for the entire reserved region. 2082 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2083 set_barrier_set(rem_set()->bs()); 2084 if (barrier_set()->is_a(BarrierSet::ModRef)) { 2085 _mr_bs = (ModRefBarrierSet*)_barrier_set; 2086 } else { 2087 vm_exit_during_initialization("G1 requires a mod ref bs."); 2088 return JNI_ENOMEM; 2089 } 2090 2091 // Also create a G1 rem set. 2092 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) { 2093 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs()); 2094 } else { 2095 vm_exit_during_initialization("G1 requires a cardtable mod ref bs."); 2096 return JNI_ENOMEM; 2097 } 2098 2099 // Carve out the G1 part of the heap. 2100 2101 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2102 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2103 g1_rs.size()/HeapWordSize); 2104 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size); 2105 2106 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set()); 2107 2108 _g1_storage.initialize(g1_rs, 0); 2109 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2110 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2111 (HeapWord*) _g1_reserved.end(), 2112 _expansion_regions); 2113 2114 // Do later initialization work for concurrent refinement. 2115 _cg1r->init(); 2116 2117 // 6843694 - ensure that the maximum region index can fit 2118 // in the remembered set structures. 2119 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2120 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2121 2122 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2123 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2124 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2125 "too many cards per region"); 2126 2127 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1); 2128 2129 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2130 heap_word_size(init_byte_size)); 2131 2132 _g1h = this; 2133 2134 _in_cset_fast_test_length = max_regions(); 2135 _in_cset_fast_test_base = 2136 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC); 2137 2138 // We're biasing _in_cset_fast_test to avoid subtracting the 2139 // beginning of the heap every time we want to index; basically 2140 // it's the same with what we do with the card table. 2141 _in_cset_fast_test = _in_cset_fast_test_base - 2142 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes); 2143 2144 // Clear the _cset_fast_test bitmap in anticipation of adding 2145 // regions to the incremental collection set for the first 2146 // evacuation pause. 2147 clear_cset_fast_test(); 2148 2149 // Create the ConcurrentMark data structure and thread. 2150 // (Must do this late, so that "max_regions" is defined.) 2151 _cm = new ConcurrentMark(heap_rs, max_regions()); 2152 _cmThread = _cm->cmThread(); 2153 2154 // Initialize the from_card cache structure of HeapRegionRemSet. 2155 HeapRegionRemSet::init_heap(max_regions()); 2156 2157 // Now expand into the initial heap size. 2158 if (!expand(init_byte_size)) { 2159 vm_exit_during_initialization("Failed to allocate initial heap."); 2160 return JNI_ENOMEM; 2161 } 2162 2163 // Perform any initialization actions delegated to the policy. 2164 g1_policy()->init(); 2165 2166 _refine_cte_cl = 2167 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(), 2168 g1_rem_set(), 2169 concurrent_g1_refine()); 2170 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 2171 2172 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2173 SATB_Q_FL_lock, 2174 G1SATBProcessCompletedThreshold, 2175 Shared_SATB_Q_lock); 2176 2177 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2178 DirtyCardQ_FL_lock, 2179 concurrent_g1_refine()->yellow_zone(), 2180 concurrent_g1_refine()->red_zone(), 2181 Shared_DirtyCardQ_lock); 2182 2183 if (G1DeferredRSUpdate) { 2184 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2185 DirtyCardQ_FL_lock, 2186 -1, // never trigger processing 2187 -1, // no limit on length 2188 Shared_DirtyCardQ_lock, 2189 &JavaThread::dirty_card_queue_set()); 2190 } 2191 2192 // Initialize the card queue set used to hold cards containing 2193 // references into the collection set. 2194 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, 2195 DirtyCardQ_FL_lock, 2196 -1, // never trigger processing 2197 -1, // no limit on length 2198 Shared_DirtyCardQ_lock, 2199 &JavaThread::dirty_card_queue_set()); 2200 2201 // In case we're keeping closure specialization stats, initialize those 2202 // counts and that mechanism. 2203 SpecializationStats::clear(); 2204 2205 // Here we allocate the dummy full region that is required by the 2206 // G1AllocRegion class. If we don't pass an address in the reserved 2207 // space here, lots of asserts fire. 2208 2209 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2210 _g1_reserved.start()); 2211 // We'll re-use the same region whether the alloc region will 2212 // require BOT updates or not and, if it doesn't, then a non-young 2213 // region will complain that it cannot support allocations without 2214 // BOT updates. So we'll tag the dummy region as young to avoid that. 2215 dummy_region->set_young(); 2216 // Make sure it's full. 2217 dummy_region->set_top(dummy_region->end()); 2218 G1AllocRegion::setup(this, dummy_region); 2219 2220 init_mutator_alloc_region(); 2221 2222 // Do create of the monitoring and management support so that 2223 // values in the heap have been properly initialized. 2224 _g1mm = new G1MonitoringSupport(this); 2225 2226 return JNI_OK; 2227 } 2228 2229 void G1CollectedHeap::ref_processing_init() { 2230 // Reference processing in G1 currently works as follows: 2231 // 2232 // * There are two reference processor instances. One is 2233 // used to record and process discovered references 2234 // during concurrent marking; the other is used to 2235 // record and process references during STW pauses 2236 // (both full and incremental). 2237 // * Both ref processors need to 'span' the entire heap as 2238 // the regions in the collection set may be dotted around. 2239 // 2240 // * For the concurrent marking ref processor: 2241 // * Reference discovery is enabled at initial marking. 2242 // * Reference discovery is disabled and the discovered 2243 // references processed etc during remarking. 2244 // * Reference discovery is MT (see below). 2245 // * Reference discovery requires a barrier (see below). 2246 // * Reference processing may or may not be MT 2247 // (depending on the value of ParallelRefProcEnabled 2248 // and ParallelGCThreads). 2249 // * A full GC disables reference discovery by the CM 2250 // ref processor and abandons any entries on it's 2251 // discovered lists. 2252 // 2253 // * For the STW processor: 2254 // * Non MT discovery is enabled at the start of a full GC. 2255 // * Processing and enqueueing during a full GC is non-MT. 2256 // * During a full GC, references are processed after marking. 2257 // 2258 // * Discovery (may or may not be MT) is enabled at the start 2259 // of an incremental evacuation pause. 2260 // * References are processed near the end of a STW evacuation pause. 2261 // * For both types of GC: 2262 // * Discovery is atomic - i.e. not concurrent. 2263 // * Reference discovery will not need a barrier. 2264 2265 SharedHeap::ref_processing_init(); 2266 MemRegion mr = reserved_region(); 2267 2268 // Concurrent Mark ref processor 2269 _ref_processor_cm = 2270 new ReferenceProcessor(mr, // span 2271 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2272 // mt processing 2273 (int) ParallelGCThreads, 2274 // degree of mt processing 2275 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2276 // mt discovery 2277 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2278 // degree of mt discovery 2279 false, 2280 // Reference discovery is not atomic 2281 &_is_alive_closure_cm, 2282 // is alive closure 2283 // (for efficiency/performance) 2284 true); 2285 // Setting next fields of discovered 2286 // lists requires a barrier. 2287 2288 // STW ref processor 2289 _ref_processor_stw = 2290 new ReferenceProcessor(mr, // span 2291 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2292 // mt processing 2293 MAX2((int)ParallelGCThreads, 1), 2294 // degree of mt processing 2295 (ParallelGCThreads > 1), 2296 // mt discovery 2297 MAX2((int)ParallelGCThreads, 1), 2298 // degree of mt discovery 2299 true, 2300 // Reference discovery is atomic 2301 &_is_alive_closure_stw, 2302 // is alive closure 2303 // (for efficiency/performance) 2304 false); 2305 // Setting next fields of discovered 2306 // lists requires a barrier. 2307 } 2308 2309 size_t G1CollectedHeap::capacity() const { 2310 return _g1_committed.byte_size(); 2311 } 2312 2313 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2314 assert(!hr->continuesHumongous(), "pre-condition"); 2315 hr->reset_gc_time_stamp(); 2316 if (hr->startsHumongous()) { 2317 uint first_index = hr->hrs_index() + 1; 2318 uint last_index = hr->last_hc_index(); 2319 for (uint i = first_index; i < last_index; i += 1) { 2320 HeapRegion* chr = region_at(i); 2321 assert(chr->continuesHumongous(), "sanity"); 2322 chr->reset_gc_time_stamp(); 2323 } 2324 } 2325 } 2326 2327 #ifndef PRODUCT 2328 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2329 private: 2330 unsigned _gc_time_stamp; 2331 bool _failures; 2332 2333 public: 2334 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2335 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2336 2337 virtual bool doHeapRegion(HeapRegion* hr) { 2338 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2339 if (_gc_time_stamp != region_gc_time_stamp) { 2340 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2341 "expected %d", HR_FORMAT_PARAMS(hr), 2342 region_gc_time_stamp, _gc_time_stamp); 2343 _failures = true; 2344 } 2345 return false; 2346 } 2347 2348 bool failures() { return _failures; } 2349 }; 2350 2351 void G1CollectedHeap::check_gc_time_stamps() { 2352 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2353 heap_region_iterate(&cl); 2354 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2355 } 2356 #endif // PRODUCT 2357 2358 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2359 DirtyCardQueue* into_cset_dcq, 2360 bool concurrent, 2361 int worker_i) { 2362 // Clean cards in the hot card cache 2363 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2364 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2365 2366 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2367 int n_completed_buffers = 0; 2368 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2369 n_completed_buffers++; 2370 } 2371 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2372 dcqs.clear_n_completed_buffers(); 2373 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2374 } 2375 2376 2377 // Computes the sum of the storage used by the various regions. 2378 2379 size_t G1CollectedHeap::used() const { 2380 assert(Heap_lock->owner() != NULL, 2381 "Should be owned on this thread's behalf."); 2382 size_t result = _summary_bytes_used; 2383 // Read only once in case it is set to NULL concurrently 2384 HeapRegion* hr = _mutator_alloc_region.get(); 2385 if (hr != NULL) 2386 result += hr->used(); 2387 return result; 2388 } 2389 2390 size_t G1CollectedHeap::used_unlocked() const { 2391 size_t result = _summary_bytes_used; 2392 return result; 2393 } 2394 2395 class SumUsedClosure: public HeapRegionClosure { 2396 size_t _used; 2397 public: 2398 SumUsedClosure() : _used(0) {} 2399 bool doHeapRegion(HeapRegion* r) { 2400 if (!r->continuesHumongous()) { 2401 _used += r->used(); 2402 } 2403 return false; 2404 } 2405 size_t result() { return _used; } 2406 }; 2407 2408 size_t G1CollectedHeap::recalculate_used() const { 2409 SumUsedClosure blk; 2410 heap_region_iterate(&blk); 2411 return blk.result(); 2412 } 2413 2414 size_t G1CollectedHeap::unsafe_max_alloc() { 2415 if (free_regions() > 0) return HeapRegion::GrainBytes; 2416 // otherwise, is there space in the current allocation region? 2417 2418 // We need to store the current allocation region in a local variable 2419 // here. The problem is that this method doesn't take any locks and 2420 // there may be other threads which overwrite the current allocation 2421 // region field. attempt_allocation(), for example, sets it to NULL 2422 // and this can happen *after* the NULL check here but before the call 2423 // to free(), resulting in a SIGSEGV. Note that this doesn't appear 2424 // to be a problem in the optimized build, since the two loads of the 2425 // current allocation region field are optimized away. 2426 HeapRegion* hr = _mutator_alloc_region.get(); 2427 if (hr == NULL) { 2428 return 0; 2429 } 2430 return hr->free(); 2431 } 2432 2433 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2434 switch (cause) { 2435 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2436 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2437 case GCCause::_g1_humongous_allocation: return true; 2438 default: return false; 2439 } 2440 } 2441 2442 #ifndef PRODUCT 2443 void G1CollectedHeap::allocate_dummy_regions() { 2444 // Let's fill up most of the region 2445 size_t word_size = HeapRegion::GrainWords - 1024; 2446 // And as a result the region we'll allocate will be humongous. 2447 guarantee(isHumongous(word_size), "sanity"); 2448 2449 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2450 // Let's use the existing mechanism for the allocation 2451 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2452 if (dummy_obj != NULL) { 2453 MemRegion mr(dummy_obj, word_size); 2454 CollectedHeap::fill_with_object(mr); 2455 } else { 2456 // If we can't allocate once, we probably cannot allocate 2457 // again. Let's get out of the loop. 2458 break; 2459 } 2460 } 2461 } 2462 #endif // !PRODUCT 2463 2464 void G1CollectedHeap::increment_old_marking_cycles_started() { 2465 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2466 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2467 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2468 _old_marking_cycles_started, _old_marking_cycles_completed)); 2469 2470 _old_marking_cycles_started++; 2471 } 2472 2473 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2474 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2475 2476 // We assume that if concurrent == true, then the caller is a 2477 // concurrent thread that was joined the Suspendible Thread 2478 // Set. If there's ever a cheap way to check this, we should add an 2479 // assert here. 2480 2481 // Given that this method is called at the end of a Full GC or of a 2482 // concurrent cycle, and those can be nested (i.e., a Full GC can 2483 // interrupt a concurrent cycle), the number of full collections 2484 // completed should be either one (in the case where there was no 2485 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2486 // behind the number of full collections started. 2487 2488 // This is the case for the inner caller, i.e. a Full GC. 2489 assert(concurrent || 2490 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2491 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2492 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2493 "is inconsistent with _old_marking_cycles_completed = %u", 2494 _old_marking_cycles_started, _old_marking_cycles_completed)); 2495 2496 // This is the case for the outer caller, i.e. the concurrent cycle. 2497 assert(!concurrent || 2498 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2499 err_msg("for outer caller (concurrent cycle): " 2500 "_old_marking_cycles_started = %u " 2501 "is inconsistent with _old_marking_cycles_completed = %u", 2502 _old_marking_cycles_started, _old_marking_cycles_completed)); 2503 2504 _old_marking_cycles_completed += 1; 2505 2506 // We need to clear the "in_progress" flag in the CM thread before 2507 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2508 // is set) so that if a waiter requests another System.gc() it doesn't 2509 // incorrectly see that a marking cycle is still in progress. 2510 if (concurrent) { 2511 _cmThread->clear_in_progress(); 2512 } 2513 2514 // This notify_all() will ensure that a thread that called 2515 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2516 // and it's waiting for a full GC to finish will be woken up. It is 2517 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2518 FullGCCount_lock->notify_all(); 2519 } 2520 2521 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) { 2522 _concurrent_cycle_started = true; 2523 _gc_timer_cm->register_gc_start(start_time); 2524 2525 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2526 trace_heap_before_gc(_gc_tracer_cm); 2527 } 2528 2529 void G1CollectedHeap::register_concurrent_cycle_end() { 2530 if (_concurrent_cycle_started) { 2531 _gc_timer_cm->register_gc_end(os::elapsed_counter()); 2532 2533 if (_cm->has_aborted()) { 2534 _gc_tracer_cm->report_concurrent_mode_failure(); 2535 } 2536 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2537 2538 _concurrent_cycle_started = false; 2539 } 2540 } 2541 2542 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2543 if (_concurrent_cycle_started) { 2544 trace_heap_after_gc(_gc_tracer_cm); 2545 } 2546 } 2547 2548 G1YCType G1CollectedHeap::yc_type() { 2549 bool is_young = g1_policy()->gcs_are_young(); 2550 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2551 bool is_during_mark = mark_in_progress(); 2552 2553 if (is_initial_mark) { 2554 return InitialMark; 2555 } else if (is_during_mark) { 2556 return DuringMark; 2557 } else if (is_young) { 2558 return Normal; 2559 } else { 2560 return Mixed; 2561 } 2562 } 2563 2564 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { 2565 assert_at_safepoint(true /* should_be_vm_thread */); 2566 GCCauseSetter gcs(this, cause); 2567 switch (cause) { 2568 case GCCause::_heap_inspection: 2569 case GCCause::_heap_dump: { 2570 HandleMark hm; 2571 do_full_collection(false); // don't clear all soft refs 2572 break; 2573 } 2574 default: // XXX FIX ME 2575 ShouldNotReachHere(); // Unexpected use of this function 2576 } 2577 } 2578 2579 void G1CollectedHeap::collect(GCCause::Cause cause) { 2580 assert_heap_not_locked(); 2581 2582 unsigned int gc_count_before; 2583 unsigned int old_marking_count_before; 2584 bool retry_gc; 2585 2586 do { 2587 retry_gc = false; 2588 2589 { 2590 MutexLocker ml(Heap_lock); 2591 2592 // Read the GC count while holding the Heap_lock 2593 gc_count_before = total_collections(); 2594 old_marking_count_before = _old_marking_cycles_started; 2595 } 2596 2597 if (should_do_concurrent_full_gc(cause)) { 2598 // Schedule an initial-mark evacuation pause that will start a 2599 // concurrent cycle. We're setting word_size to 0 which means that 2600 // we are not requesting a post-GC allocation. 2601 VM_G1IncCollectionPause op(gc_count_before, 2602 0, /* word_size */ 2603 true, /* should_initiate_conc_mark */ 2604 g1_policy()->max_pause_time_ms(), 2605 cause); 2606 2607 VMThread::execute(&op); 2608 if (!op.pause_succeeded()) { 2609 if (old_marking_count_before == _old_marking_cycles_started) { 2610 retry_gc = op.should_retry_gc(); 2611 } else { 2612 // A Full GC happened while we were trying to schedule the 2613 // initial-mark GC. No point in starting a new cycle given 2614 // that the whole heap was collected anyway. 2615 } 2616 2617 if (retry_gc) { 2618 if (GC_locker::is_active_and_needs_gc()) { 2619 GC_locker::stall_until_clear(); 2620 } 2621 } 2622 } 2623 } else { 2624 if (cause == GCCause::_gc_locker 2625 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2626 2627 // Schedule a standard evacuation pause. We're setting word_size 2628 // to 0 which means that we are not requesting a post-GC allocation. 2629 VM_G1IncCollectionPause op(gc_count_before, 2630 0, /* word_size */ 2631 false, /* should_initiate_conc_mark */ 2632 g1_policy()->max_pause_time_ms(), 2633 cause); 2634 VMThread::execute(&op); 2635 } else { 2636 // Schedule a Full GC. 2637 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2638 VMThread::execute(&op); 2639 } 2640 } 2641 } while (retry_gc); 2642 } 2643 2644 bool G1CollectedHeap::is_in(const void* p) const { 2645 if (_g1_committed.contains(p)) { 2646 // Given that we know that p is in the committed space, 2647 // heap_region_containing_raw() should successfully 2648 // return the containing region. 2649 HeapRegion* hr = heap_region_containing_raw(p); 2650 return hr->is_in(p); 2651 } else { 2652 return _perm_gen->as_gen()->is_in(p); 2653 } 2654 } 2655 2656 // Iteration functions. 2657 2658 // Iterates an OopClosure over all ref-containing fields of objects 2659 // within a HeapRegion. 2660 2661 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2662 MemRegion _mr; 2663 OopClosure* _cl; 2664 public: 2665 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl) 2666 : _mr(mr), _cl(cl) {} 2667 bool doHeapRegion(HeapRegion* r) { 2668 if (!r->continuesHumongous()) { 2669 r->oop_iterate(_cl); 2670 } 2671 return false; 2672 } 2673 }; 2674 2675 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) { 2676 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2677 heap_region_iterate(&blk); 2678 if (do_perm) { 2679 perm_gen()->oop_iterate(cl); 2680 } 2681 } 2682 2683 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) { 2684 IterateOopClosureRegionClosure blk(mr, cl); 2685 heap_region_iterate(&blk); 2686 if (do_perm) { 2687 perm_gen()->oop_iterate(cl); 2688 } 2689 } 2690 2691 // Iterates an ObjectClosure over all objects within a HeapRegion. 2692 2693 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2694 ObjectClosure* _cl; 2695 public: 2696 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2697 bool doHeapRegion(HeapRegion* r) { 2698 if (! r->continuesHumongous()) { 2699 r->object_iterate(_cl); 2700 } 2701 return false; 2702 } 2703 }; 2704 2705 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) { 2706 IterateObjectClosureRegionClosure blk(cl); 2707 heap_region_iterate(&blk); 2708 if (do_perm) { 2709 perm_gen()->object_iterate(cl); 2710 } 2711 } 2712 2713 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) { 2714 // FIXME: is this right? 2715 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap"); 2716 } 2717 2718 // Calls a SpaceClosure on a HeapRegion. 2719 2720 class SpaceClosureRegionClosure: public HeapRegionClosure { 2721 SpaceClosure* _cl; 2722 public: 2723 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2724 bool doHeapRegion(HeapRegion* r) { 2725 _cl->do_space(r); 2726 return false; 2727 } 2728 }; 2729 2730 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2731 SpaceClosureRegionClosure blk(cl); 2732 heap_region_iterate(&blk); 2733 } 2734 2735 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2736 _hrs.iterate(cl); 2737 } 2738 2739 void 2740 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2741 uint worker_id, 2742 uint no_of_par_workers, 2743 jint claim_value) { 2744 const uint regions = n_regions(); 2745 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2746 no_of_par_workers : 2747 1); 2748 assert(UseDynamicNumberOfGCThreads || 2749 no_of_par_workers == workers()->total_workers(), 2750 "Non dynamic should use fixed number of workers"); 2751 // try to spread out the starting points of the workers 2752 const HeapRegion* start_hr = 2753 start_region_for_worker(worker_id, no_of_par_workers); 2754 const uint start_index = start_hr->hrs_index(); 2755 2756 // each worker will actually look at all regions 2757 for (uint count = 0; count < regions; ++count) { 2758 const uint index = (start_index + count) % regions; 2759 assert(0 <= index && index < regions, "sanity"); 2760 HeapRegion* r = region_at(index); 2761 // we'll ignore "continues humongous" regions (we'll process them 2762 // when we come across their corresponding "start humongous" 2763 // region) and regions already claimed 2764 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2765 continue; 2766 } 2767 // OK, try to claim it 2768 if (r->claimHeapRegion(claim_value)) { 2769 // success! 2770 assert(!r->continuesHumongous(), "sanity"); 2771 if (r->startsHumongous()) { 2772 // If the region is "starts humongous" we'll iterate over its 2773 // "continues humongous" first; in fact we'll do them 2774 // first. The order is important. In on case, calling the 2775 // closure on the "starts humongous" region might de-allocate 2776 // and clear all its "continues humongous" regions and, as a 2777 // result, we might end up processing them twice. So, we'll do 2778 // them first (notice: most closures will ignore them anyway) and 2779 // then we'll do the "starts humongous" region. 2780 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2781 HeapRegion* chr = region_at(ch_index); 2782 2783 // if the region has already been claimed or it's not 2784 // "continues humongous" we're done 2785 if (chr->claim_value() == claim_value || 2786 !chr->continuesHumongous()) { 2787 break; 2788 } 2789 2790 // Noone should have claimed it directly. We can given 2791 // that we claimed its "starts humongous" region. 2792 assert(chr->claim_value() != claim_value, "sanity"); 2793 assert(chr->humongous_start_region() == r, "sanity"); 2794 2795 if (chr->claimHeapRegion(claim_value)) { 2796 // we should always be able to claim it; noone else should 2797 // be trying to claim this region 2798 2799 bool res2 = cl->doHeapRegion(chr); 2800 assert(!res2, "Should not abort"); 2801 2802 // Right now, this holds (i.e., no closure that actually 2803 // does something with "continues humongous" regions 2804 // clears them). We might have to weaken it in the future, 2805 // but let's leave these two asserts here for extra safety. 2806 assert(chr->continuesHumongous(), "should still be the case"); 2807 assert(chr->humongous_start_region() == r, "sanity"); 2808 } else { 2809 guarantee(false, "we should not reach here"); 2810 } 2811 } 2812 } 2813 2814 assert(!r->continuesHumongous(), "sanity"); 2815 bool res = cl->doHeapRegion(r); 2816 assert(!res, "Should not abort"); 2817 } 2818 } 2819 } 2820 2821 class ResetClaimValuesClosure: public HeapRegionClosure { 2822 public: 2823 bool doHeapRegion(HeapRegion* r) { 2824 r->set_claim_value(HeapRegion::InitialClaimValue); 2825 return false; 2826 } 2827 }; 2828 2829 void G1CollectedHeap::reset_heap_region_claim_values() { 2830 ResetClaimValuesClosure blk; 2831 heap_region_iterate(&blk); 2832 } 2833 2834 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2835 ResetClaimValuesClosure blk; 2836 collection_set_iterate(&blk); 2837 } 2838 2839 #ifdef ASSERT 2840 // This checks whether all regions in the heap have the correct claim 2841 // value. I also piggy-backed on this a check to ensure that the 2842 // humongous_start_region() information on "continues humongous" 2843 // regions is correct. 2844 2845 class CheckClaimValuesClosure : public HeapRegionClosure { 2846 private: 2847 jint _claim_value; 2848 uint _failures; 2849 HeapRegion* _sh_region; 2850 2851 public: 2852 CheckClaimValuesClosure(jint claim_value) : 2853 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2854 bool doHeapRegion(HeapRegion* r) { 2855 if (r->claim_value() != _claim_value) { 2856 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2857 "claim value = %d, should be %d", 2858 HR_FORMAT_PARAMS(r), 2859 r->claim_value(), _claim_value); 2860 ++_failures; 2861 } 2862 if (!r->isHumongous()) { 2863 _sh_region = NULL; 2864 } else if (r->startsHumongous()) { 2865 _sh_region = r; 2866 } else if (r->continuesHumongous()) { 2867 if (r->humongous_start_region() != _sh_region) { 2868 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2869 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2870 HR_FORMAT_PARAMS(r), 2871 r->humongous_start_region(), 2872 _sh_region); 2873 ++_failures; 2874 } 2875 } 2876 return false; 2877 } 2878 uint failures() { return _failures; } 2879 }; 2880 2881 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2882 CheckClaimValuesClosure cl(claim_value); 2883 heap_region_iterate(&cl); 2884 return cl.failures() == 0; 2885 } 2886 2887 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2888 private: 2889 jint _claim_value; 2890 uint _failures; 2891 2892 public: 2893 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2894 _claim_value(claim_value), _failures(0) { } 2895 2896 uint failures() { return _failures; } 2897 2898 bool doHeapRegion(HeapRegion* hr) { 2899 assert(hr->in_collection_set(), "how?"); 2900 assert(!hr->isHumongous(), "H-region in CSet"); 2901 if (hr->claim_value() != _claim_value) { 2902 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2903 "claim value = %d, should be %d", 2904 HR_FORMAT_PARAMS(hr), 2905 hr->claim_value(), _claim_value); 2906 _failures += 1; 2907 } 2908 return false; 2909 } 2910 }; 2911 2912 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2913 CheckClaimValuesInCSetHRClosure cl(claim_value); 2914 collection_set_iterate(&cl); 2915 return cl.failures() == 0; 2916 } 2917 #endif // ASSERT 2918 2919 // Clear the cached CSet starting regions and (more importantly) 2920 // the time stamps. Called when we reset the GC time stamp. 2921 void G1CollectedHeap::clear_cset_start_regions() { 2922 assert(_worker_cset_start_region != NULL, "sanity"); 2923 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2924 2925 int n_queues = MAX2((int)ParallelGCThreads, 1); 2926 for (int i = 0; i < n_queues; i++) { 2927 _worker_cset_start_region[i] = NULL; 2928 _worker_cset_start_region_time_stamp[i] = 0; 2929 } 2930 } 2931 2932 // Given the id of a worker, obtain or calculate a suitable 2933 // starting region for iterating over the current collection set. 2934 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) { 2935 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2936 2937 HeapRegion* result = NULL; 2938 unsigned gc_time_stamp = get_gc_time_stamp(); 2939 2940 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2941 // Cached starting region for current worker was set 2942 // during the current pause - so it's valid. 2943 // Note: the cached starting heap region may be NULL 2944 // (when the collection set is empty). 2945 result = _worker_cset_start_region[worker_i]; 2946 assert(result == NULL || result->in_collection_set(), "sanity"); 2947 return result; 2948 } 2949 2950 // The cached entry was not valid so let's calculate 2951 // a suitable starting heap region for this worker. 2952 2953 // We want the parallel threads to start their collection 2954 // set iteration at different collection set regions to 2955 // avoid contention. 2956 // If we have: 2957 // n collection set regions 2958 // p threads 2959 // Then thread t will start at region floor ((t * n) / p) 2960 2961 result = g1_policy()->collection_set(); 2962 if (G1CollectedHeap::use_parallel_gc_threads()) { 2963 uint cs_size = g1_policy()->cset_region_length(); 2964 uint active_workers = workers()->active_workers(); 2965 assert(UseDynamicNumberOfGCThreads || 2966 active_workers == workers()->total_workers(), 2967 "Unless dynamic should use total workers"); 2968 2969 uint end_ind = (cs_size * worker_i) / active_workers; 2970 uint start_ind = 0; 2971 2972 if (worker_i > 0 && 2973 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2974 // Previous workers starting region is valid 2975 // so let's iterate from there 2976 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2977 result = _worker_cset_start_region[worker_i - 1]; 2978 } 2979 2980 for (uint i = start_ind; i < end_ind; i++) { 2981 result = result->next_in_collection_set(); 2982 } 2983 } 2984 2985 // Note: the calculated starting heap region may be NULL 2986 // (when the collection set is empty). 2987 assert(result == NULL || result->in_collection_set(), "sanity"); 2988 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2989 "should be updated only once per pause"); 2990 _worker_cset_start_region[worker_i] = result; 2991 OrderAccess::storestore(); 2992 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2993 return result; 2994 } 2995 2996 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2997 uint no_of_par_workers) { 2998 uint worker_num = 2999 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 3000 assert(UseDynamicNumberOfGCThreads || 3001 no_of_par_workers == workers()->total_workers(), 3002 "Non dynamic should use fixed number of workers"); 3003 const uint start_index = n_regions() * worker_i / worker_num; 3004 return region_at(start_index); 3005 } 3006 3007 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 3008 HeapRegion* r = g1_policy()->collection_set(); 3009 while (r != NULL) { 3010 HeapRegion* next = r->next_in_collection_set(); 3011 if (cl->doHeapRegion(r)) { 3012 cl->incomplete(); 3013 return; 3014 } 3015 r = next; 3016 } 3017 } 3018 3019 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 3020 HeapRegionClosure *cl) { 3021 if (r == NULL) { 3022 // The CSet is empty so there's nothing to do. 3023 return; 3024 } 3025 3026 assert(r->in_collection_set(), 3027 "Start region must be a member of the collection set."); 3028 HeapRegion* cur = r; 3029 while (cur != NULL) { 3030 HeapRegion* next = cur->next_in_collection_set(); 3031 if (cl->doHeapRegion(cur) && false) { 3032 cl->incomplete(); 3033 return; 3034 } 3035 cur = next; 3036 } 3037 cur = g1_policy()->collection_set(); 3038 while (cur != r) { 3039 HeapRegion* next = cur->next_in_collection_set(); 3040 if (cl->doHeapRegion(cur) && false) { 3041 cl->incomplete(); 3042 return; 3043 } 3044 cur = next; 3045 } 3046 } 3047 3048 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 3049 return n_regions() > 0 ? region_at(0) : NULL; 3050 } 3051 3052 3053 Space* G1CollectedHeap::space_containing(const void* addr) const { 3054 Space* res = heap_region_containing(addr); 3055 if (res == NULL) 3056 res = perm_gen()->space_containing(addr); 3057 return res; 3058 } 3059 3060 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 3061 Space* sp = space_containing(addr); 3062 if (sp != NULL) { 3063 return sp->block_start(addr); 3064 } 3065 return NULL; 3066 } 3067 3068 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 3069 Space* sp = space_containing(addr); 3070 assert(sp != NULL, "block_size of address outside of heap"); 3071 return sp->block_size(addr); 3072 } 3073 3074 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 3075 Space* sp = space_containing(addr); 3076 return sp->block_is_obj(addr); 3077 } 3078 3079 bool G1CollectedHeap::supports_tlab_allocation() const { 3080 return true; 3081 } 3082 3083 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 3084 return HeapRegion::GrainBytes; 3085 } 3086 3087 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 3088 // Return the remaining space in the cur alloc region, but not less than 3089 // the min TLAB size. 3090 3091 // Also, this value can be at most the humongous object threshold, 3092 // since we can't allow tlabs to grow big enough to accommodate 3093 // humongous objects. 3094 3095 HeapRegion* hr = _mutator_alloc_region.get(); 3096 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize; 3097 if (hr == NULL) { 3098 return max_tlab_size; 3099 } else { 3100 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size); 3101 } 3102 } 3103 3104 size_t G1CollectedHeap::max_capacity() const { 3105 return _g1_reserved.byte_size(); 3106 } 3107 3108 jlong G1CollectedHeap::millis_since_last_gc() { 3109 // assert(false, "NYI"); 3110 return 0; 3111 } 3112 3113 void G1CollectedHeap::prepare_for_verify() { 3114 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3115 ensure_parsability(false); 3116 } 3117 g1_rem_set()->prepare_for_verify(); 3118 } 3119 3120 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3121 VerifyOption vo) { 3122 switch (vo) { 3123 case VerifyOption_G1UsePrevMarking: 3124 return hr->obj_allocated_since_prev_marking(obj); 3125 case VerifyOption_G1UseNextMarking: 3126 return hr->obj_allocated_since_next_marking(obj); 3127 case VerifyOption_G1UseMarkWord: 3128 return false; 3129 default: 3130 ShouldNotReachHere(); 3131 } 3132 return false; // keep some compilers happy 3133 } 3134 3135 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3136 switch (vo) { 3137 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3138 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3139 case VerifyOption_G1UseMarkWord: return NULL; 3140 default: ShouldNotReachHere(); 3141 } 3142 return NULL; // keep some compilers happy 3143 } 3144 3145 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3146 switch (vo) { 3147 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3148 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3149 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3150 default: ShouldNotReachHere(); 3151 } 3152 return false; // keep some compilers happy 3153 } 3154 3155 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3156 switch (vo) { 3157 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3158 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3159 case VerifyOption_G1UseMarkWord: return "NONE"; 3160 default: ShouldNotReachHere(); 3161 } 3162 return NULL; // keep some compilers happy 3163 } 3164 3165 class VerifyLivenessOopClosure: public OopClosure { 3166 G1CollectedHeap* _g1h; 3167 VerifyOption _vo; 3168 public: 3169 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3170 _g1h(g1h), _vo(vo) 3171 { } 3172 void do_oop(narrowOop *p) { do_oop_work(p); } 3173 void do_oop( oop *p) { do_oop_work(p); } 3174 3175 template <class T> void do_oop_work(T *p) { 3176 oop obj = oopDesc::load_decode_heap_oop(p); 3177 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3178 "Dead object referenced by a not dead object"); 3179 } 3180 }; 3181 3182 class VerifyObjsInRegionClosure: public ObjectClosure { 3183 private: 3184 G1CollectedHeap* _g1h; 3185 size_t _live_bytes; 3186 HeapRegion *_hr; 3187 VerifyOption _vo; 3188 public: 3189 // _vo == UsePrevMarking -> use "prev" marking information, 3190 // _vo == UseNextMarking -> use "next" marking information, 3191 // _vo == UseMarkWord -> use mark word from object header. 3192 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3193 : _live_bytes(0), _hr(hr), _vo(vo) { 3194 _g1h = G1CollectedHeap::heap(); 3195 } 3196 void do_object(oop o) { 3197 VerifyLivenessOopClosure isLive(_g1h, _vo); 3198 assert(o != NULL, "Huh?"); 3199 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3200 // If the object is alive according to the mark word, 3201 // then verify that the marking information agrees. 3202 // Note we can't verify the contra-positive of the 3203 // above: if the object is dead (according to the mark 3204 // word), it may not be marked, or may have been marked 3205 // but has since became dead, or may have been allocated 3206 // since the last marking. 3207 if (_vo == VerifyOption_G1UseMarkWord) { 3208 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3209 } 3210 3211 o->oop_iterate(&isLive); 3212 if (!_hr->obj_allocated_since_prev_marking(o)) { 3213 size_t obj_size = o->size(); // Make sure we don't overflow 3214 _live_bytes += (obj_size * HeapWordSize); 3215 } 3216 } 3217 } 3218 size_t live_bytes() { return _live_bytes; } 3219 }; 3220 3221 class PrintObjsInRegionClosure : public ObjectClosure { 3222 HeapRegion *_hr; 3223 G1CollectedHeap *_g1; 3224 public: 3225 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3226 _g1 = G1CollectedHeap::heap(); 3227 }; 3228 3229 void do_object(oop o) { 3230 if (o != NULL) { 3231 HeapWord *start = (HeapWord *) o; 3232 size_t word_sz = o->size(); 3233 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3234 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3235 (void*) o, word_sz, 3236 _g1->isMarkedPrev(o), 3237 _g1->isMarkedNext(o), 3238 _hr->obj_allocated_since_prev_marking(o)); 3239 HeapWord *end = start + word_sz; 3240 HeapWord *cur; 3241 int *val; 3242 for (cur = start; cur < end; cur++) { 3243 val = (int *) cur; 3244 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3245 } 3246 } 3247 } 3248 }; 3249 3250 class VerifyRegionClosure: public HeapRegionClosure { 3251 private: 3252 bool _par; 3253 VerifyOption _vo; 3254 bool _failures; 3255 public: 3256 // _vo == UsePrevMarking -> use "prev" marking information, 3257 // _vo == UseNextMarking -> use "next" marking information, 3258 // _vo == UseMarkWord -> use mark word from object header. 3259 VerifyRegionClosure(bool par, VerifyOption vo) 3260 : _par(par), 3261 _vo(vo), 3262 _failures(false) {} 3263 3264 bool failures() { 3265 return _failures; 3266 } 3267 3268 bool doHeapRegion(HeapRegion* r) { 3269 if (!r->continuesHumongous()) { 3270 bool failures = false; 3271 r->verify(_vo, &failures); 3272 if (failures) { 3273 _failures = true; 3274 } else { 3275 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3276 r->object_iterate(¬_dead_yet_cl); 3277 if (_vo != VerifyOption_G1UseNextMarking) { 3278 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3279 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3280 "max_live_bytes "SIZE_FORMAT" " 3281 "< calculated "SIZE_FORMAT, 3282 r->bottom(), r->end(), 3283 r->max_live_bytes(), 3284 not_dead_yet_cl.live_bytes()); 3285 _failures = true; 3286 } 3287 } else { 3288 // When vo == UseNextMarking we cannot currently do a sanity 3289 // check on the live bytes as the calculation has not been 3290 // finalized yet. 3291 } 3292 } 3293 } 3294 return false; // stop the region iteration if we hit a failure 3295 } 3296 }; 3297 3298 class VerifyRootsClosure: public OopsInGenClosure { 3299 private: 3300 G1CollectedHeap* _g1h; 3301 VerifyOption _vo; 3302 bool _failures; 3303 public: 3304 // _vo == UsePrevMarking -> use "prev" marking information, 3305 // _vo == UseNextMarking -> use "next" marking information, 3306 // _vo == UseMarkWord -> use mark word from object header. 3307 VerifyRootsClosure(VerifyOption vo) : 3308 _g1h(G1CollectedHeap::heap()), 3309 _vo(vo), 3310 _failures(false) { } 3311 3312 bool failures() { return _failures; } 3313 3314 template <class T> void do_oop_nv(T* p) { 3315 T heap_oop = oopDesc::load_heap_oop(p); 3316 if (!oopDesc::is_null(heap_oop)) { 3317 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3318 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3319 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3320 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3321 if (_vo == VerifyOption_G1UseMarkWord) { 3322 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3323 } 3324 obj->print_on(gclog_or_tty); 3325 _failures = true; 3326 } 3327 } 3328 } 3329 3330 void do_oop(oop* p) { do_oop_nv(p); } 3331 void do_oop(narrowOop* p) { do_oop_nv(p); } 3332 }; 3333 3334 // This is the task used for parallel heap verification. 3335 3336 class G1ParVerifyTask: public AbstractGangTask { 3337 private: 3338 G1CollectedHeap* _g1h; 3339 VerifyOption _vo; 3340 bool _failures; 3341 3342 public: 3343 // _vo == UsePrevMarking -> use "prev" marking information, 3344 // _vo == UseNextMarking -> use "next" marking information, 3345 // _vo == UseMarkWord -> use mark word from object header. 3346 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3347 AbstractGangTask("Parallel verify task"), 3348 _g1h(g1h), 3349 _vo(vo), 3350 _failures(false) { } 3351 3352 bool failures() { 3353 return _failures; 3354 } 3355 3356 void work(uint worker_id) { 3357 HandleMark hm; 3358 VerifyRegionClosure blk(true, _vo); 3359 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3360 _g1h->workers()->active_workers(), 3361 HeapRegion::ParVerifyClaimValue); 3362 if (blk.failures()) { 3363 _failures = true; 3364 } 3365 } 3366 }; 3367 3368 void G1CollectedHeap::verify(bool silent) { 3369 verify(silent, VerifyOption_G1UsePrevMarking); 3370 } 3371 3372 void G1CollectedHeap::verify(bool silent, 3373 VerifyOption vo) { 3374 if (SafepointSynchronize::is_at_safepoint()) { 3375 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); } 3376 VerifyRootsClosure rootsCl(vo); 3377 3378 assert(Thread::current()->is_VM_thread(), 3379 "Expected to be executed serially by the VM thread at this point"); 3380 3381 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false); 3382 3383 // We apply the relevant closures to all the oops in the 3384 // system dictionary, the string table and the code cache. 3385 const int so = SO_AllClasses | SO_Strings | SO_CodeCache; 3386 3387 process_strong_roots(true, // activate StrongRootsScope 3388 true, // we set "collecting perm gen" to true, 3389 // so we don't reset the dirty cards in the perm gen. 3390 ScanningOption(so), // roots scanning options 3391 &rootsCl, 3392 &blobsCl, 3393 &rootsCl); 3394 3395 // If we're verifying after the marking phase of a Full GC then we can't 3396 // treat the perm gen as roots into the G1 heap. Some of the objects in 3397 // the perm gen may be dead and hence not marked. If one of these dead 3398 // objects is considered to be a root then we may end up with a false 3399 // "Root location <x> points to dead ob <y>" failure. 3400 if (vo != VerifyOption_G1UseMarkWord) { 3401 // Since we used "collecting_perm_gen" == true above, we will not have 3402 // checked the refs from perm into the G1-collected heap. We check those 3403 // references explicitly below. Whether the relevant cards are dirty 3404 // is checked further below in the rem set verification. 3405 if (!silent) { gclog_or_tty->print("Permgen roots "); } 3406 perm_gen()->oop_iterate(&rootsCl); 3407 } 3408 bool failures = rootsCl.failures(); 3409 3410 if (vo != VerifyOption_G1UseMarkWord) { 3411 // If we're verifying during a full GC then the region sets 3412 // will have been torn down at the start of the GC. Therefore 3413 // verifying the region sets will fail. So we only verify 3414 // the region sets when not in a full GC. 3415 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3416 verify_region_sets(); 3417 } 3418 3419 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3420 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3421 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3422 "sanity check"); 3423 3424 G1ParVerifyTask task(this, vo); 3425 assert(UseDynamicNumberOfGCThreads || 3426 workers()->active_workers() == workers()->total_workers(), 3427 "If not dynamic should be using all the workers"); 3428 int n_workers = workers()->active_workers(); 3429 set_par_threads(n_workers); 3430 workers()->run_task(&task); 3431 set_par_threads(0); 3432 if (task.failures()) { 3433 failures = true; 3434 } 3435 3436 // Checks that the expected amount of parallel work was done. 3437 // The implication is that n_workers is > 0. 3438 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3439 "sanity check"); 3440 3441 reset_heap_region_claim_values(); 3442 3443 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3444 "sanity check"); 3445 } else { 3446 VerifyRegionClosure blk(false, vo); 3447 heap_region_iterate(&blk); 3448 if (blk.failures()) { 3449 failures = true; 3450 } 3451 } 3452 if (!silent) gclog_or_tty->print("RemSet "); 3453 rem_set()->verify(); 3454 3455 if (failures) { 3456 gclog_or_tty->print_cr("Heap:"); 3457 // It helps to have the per-region information in the output to 3458 // help us track down what went wrong. This is why we call 3459 // print_extended_on() instead of print_on(). 3460 print_extended_on(gclog_or_tty); 3461 gclog_or_tty->print_cr(""); 3462 #ifndef PRODUCT 3463 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3464 concurrent_mark()->print_reachable("at-verification-failure", 3465 vo, false /* all */); 3466 } 3467 #endif 3468 gclog_or_tty->flush(); 3469 } 3470 guarantee(!failures, "there should not have been any failures"); 3471 } else { 3472 if (!silent) 3473 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) "); 3474 } 3475 } 3476 3477 class PrintRegionClosure: public HeapRegionClosure { 3478 outputStream* _st; 3479 public: 3480 PrintRegionClosure(outputStream* st) : _st(st) {} 3481 bool doHeapRegion(HeapRegion* r) { 3482 r->print_on(_st); 3483 return false; 3484 } 3485 }; 3486 3487 void G1CollectedHeap::print_on(outputStream* st) const { 3488 st->print(" %-20s", "garbage-first heap"); 3489 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3490 capacity()/K, used_unlocked()/K); 3491 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3492 _g1_storage.low_boundary(), 3493 _g1_storage.high(), 3494 _g1_storage.high_boundary()); 3495 st->cr(); 3496 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3497 uint young_regions = _young_list->length(); 3498 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3499 (size_t) young_regions * HeapRegion::GrainBytes / K); 3500 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3501 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3502 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3503 st->cr(); 3504 perm()->as_gen()->print_on(st); 3505 } 3506 3507 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3508 print_on(st); 3509 3510 // Print the per-region information. 3511 st->cr(); 3512 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3513 "HS=humongous(starts), HC=humongous(continues), " 3514 "CS=collection set, F=free, TS=gc time stamp, " 3515 "PTAMS=previous top-at-mark-start, " 3516 "NTAMS=next top-at-mark-start)"); 3517 PrintRegionClosure blk(st); 3518 heap_region_iterate(&blk); 3519 } 3520 3521 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3522 if (G1CollectedHeap::use_parallel_gc_threads()) { 3523 workers()->print_worker_threads_on(st); 3524 } 3525 _cmThread->print_on(st); 3526 st->cr(); 3527 _cm->print_worker_threads_on(st); 3528 _cg1r->print_worker_threads_on(st); 3529 st->cr(); 3530 } 3531 3532 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3533 if (G1CollectedHeap::use_parallel_gc_threads()) { 3534 workers()->threads_do(tc); 3535 } 3536 tc->do_thread(_cmThread); 3537 _cg1r->threads_do(tc); 3538 } 3539 3540 void G1CollectedHeap::print_tracing_info() const { 3541 // We'll overload this to mean "trace GC pause statistics." 3542 if (TraceGen0Time || TraceGen1Time) { 3543 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3544 // to that. 3545 g1_policy()->print_tracing_info(); 3546 } 3547 if (G1SummarizeRSetStats) { 3548 g1_rem_set()->print_summary_info(); 3549 } 3550 if (G1SummarizeConcMark) { 3551 concurrent_mark()->print_summary_info(); 3552 } 3553 g1_policy()->print_yg_surv_rate_info(); 3554 SpecializationStats::print(); 3555 } 3556 3557 #ifndef PRODUCT 3558 // Helpful for debugging RSet issues. 3559 3560 class PrintRSetsClosure : public HeapRegionClosure { 3561 private: 3562 const char* _msg; 3563 size_t _occupied_sum; 3564 3565 public: 3566 bool doHeapRegion(HeapRegion* r) { 3567 HeapRegionRemSet* hrrs = r->rem_set(); 3568 size_t occupied = hrrs->occupied(); 3569 _occupied_sum += occupied; 3570 3571 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3572 HR_FORMAT_PARAMS(r)); 3573 if (occupied == 0) { 3574 gclog_or_tty->print_cr(" RSet is empty"); 3575 } else { 3576 hrrs->print(); 3577 } 3578 gclog_or_tty->print_cr("----------"); 3579 return false; 3580 } 3581 3582 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3583 gclog_or_tty->cr(); 3584 gclog_or_tty->print_cr("========================================"); 3585 gclog_or_tty->print_cr(msg); 3586 gclog_or_tty->cr(); 3587 } 3588 3589 ~PrintRSetsClosure() { 3590 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3591 gclog_or_tty->print_cr("========================================"); 3592 gclog_or_tty->cr(); 3593 } 3594 }; 3595 3596 void G1CollectedHeap::print_cset_rsets() { 3597 PrintRSetsClosure cl("Printing CSet RSets"); 3598 collection_set_iterate(&cl); 3599 } 3600 3601 void G1CollectedHeap::print_all_rsets() { 3602 PrintRSetsClosure cl("Printing All RSets");; 3603 heap_region_iterate(&cl); 3604 } 3605 #endif // PRODUCT 3606 3607 G1CollectedHeap* G1CollectedHeap::heap() { 3608 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3609 "not a garbage-first heap"); 3610 return _g1h; 3611 } 3612 3613 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3614 // always_do_update_barrier = false; 3615 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3616 // Call allocation profiler 3617 AllocationProfiler::iterate_since_last_gc(); 3618 // Fill TLAB's and such 3619 ensure_parsability(true); 3620 } 3621 3622 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3623 // FIXME: what is this about? 3624 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3625 // is set. 3626 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3627 "derived pointer present")); 3628 // always_do_update_barrier = true; 3629 3630 // We have just completed a GC. Update the soft reference 3631 // policy with the new heap occupancy 3632 Universe::update_heap_info_at_gc(); 3633 } 3634 3635 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3636 unsigned int gc_count_before, 3637 bool* succeeded) { 3638 assert_heap_not_locked_and_not_at_safepoint(); 3639 g1_policy()->record_stop_world_start(); 3640 VM_G1IncCollectionPause op(gc_count_before, 3641 word_size, 3642 false, /* should_initiate_conc_mark */ 3643 g1_policy()->max_pause_time_ms(), 3644 GCCause::_g1_inc_collection_pause); 3645 VMThread::execute(&op); 3646 3647 HeapWord* result = op.result(); 3648 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3649 assert(result == NULL || ret_succeeded, 3650 "the result should be NULL if the VM did not succeed"); 3651 *succeeded = ret_succeeded; 3652 3653 assert_heap_not_locked(); 3654 return result; 3655 } 3656 3657 void 3658 G1CollectedHeap::doConcurrentMark() { 3659 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3660 if (!_cmThread->in_progress()) { 3661 _cmThread->set_started(); 3662 CGC_lock->notify(); 3663 } 3664 } 3665 3666 size_t G1CollectedHeap::pending_card_num() { 3667 size_t extra_cards = 0; 3668 JavaThread *curr = Threads::first(); 3669 while (curr != NULL) { 3670 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3671 extra_cards += dcq.size(); 3672 curr = curr->next(); 3673 } 3674 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3675 size_t buffer_size = dcqs.buffer_size(); 3676 size_t buffer_num = dcqs.completed_buffers_num(); 3677 3678 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3679 // in bytes - not the number of 'entries'. We need to convert 3680 // into a number of cards. 3681 return (buffer_size * buffer_num + extra_cards) / oopSize; 3682 } 3683 3684 size_t G1CollectedHeap::cards_scanned() { 3685 return g1_rem_set()->cardsScanned(); 3686 } 3687 3688 void 3689 G1CollectedHeap::setup_surviving_young_words() { 3690 assert(_surviving_young_words == NULL, "pre-condition"); 3691 uint array_length = g1_policy()->young_cset_region_length(); 3692 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3693 if (_surviving_young_words == NULL) { 3694 vm_exit_out_of_memory(sizeof(size_t) * array_length, 3695 "Not enough space for young surv words summary."); 3696 } 3697 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3698 #ifdef ASSERT 3699 for (uint i = 0; i < array_length; ++i) { 3700 assert( _surviving_young_words[i] == 0, "memset above" ); 3701 } 3702 #endif // !ASSERT 3703 } 3704 3705 void 3706 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3707 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3708 uint array_length = g1_policy()->young_cset_region_length(); 3709 for (uint i = 0; i < array_length; ++i) { 3710 _surviving_young_words[i] += surv_young_words[i]; 3711 } 3712 } 3713 3714 void 3715 G1CollectedHeap::cleanup_surviving_young_words() { 3716 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3717 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3718 _surviving_young_words = NULL; 3719 } 3720 3721 #ifdef ASSERT 3722 class VerifyCSetClosure: public HeapRegionClosure { 3723 public: 3724 bool doHeapRegion(HeapRegion* hr) { 3725 // Here we check that the CSet region's RSet is ready for parallel 3726 // iteration. The fields that we'll verify are only manipulated 3727 // when the region is part of a CSet and is collected. Afterwards, 3728 // we reset these fields when we clear the region's RSet (when the 3729 // region is freed) so they are ready when the region is 3730 // re-allocated. The only exception to this is if there's an 3731 // evacuation failure and instead of freeing the region we leave 3732 // it in the heap. In that case, we reset these fields during 3733 // evacuation failure handling. 3734 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3735 3736 // Here's a good place to add any other checks we'd like to 3737 // perform on CSet regions. 3738 return false; 3739 } 3740 }; 3741 #endif // ASSERT 3742 3743 #if TASKQUEUE_STATS 3744 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3745 st->print_raw_cr("GC Task Stats"); 3746 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3747 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3748 } 3749 3750 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3751 print_taskqueue_stats_hdr(st); 3752 3753 TaskQueueStats totals; 3754 const int n = workers() != NULL ? workers()->total_workers() : 1; 3755 for (int i = 0; i < n; ++i) { 3756 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3757 totals += task_queue(i)->stats; 3758 } 3759 st->print_raw("tot "); totals.print(st); st->cr(); 3760 3761 DEBUG_ONLY(totals.verify()); 3762 } 3763 3764 void G1CollectedHeap::reset_taskqueue_stats() { 3765 const int n = workers() != NULL ? workers()->total_workers() : 1; 3766 for (int i = 0; i < n; ++i) { 3767 task_queue(i)->stats.reset(); 3768 } 3769 } 3770 #endif // TASKQUEUE_STATS 3771 3772 void G1CollectedHeap::log_gc_header() { 3773 if (!G1Log::fine()) { 3774 return; 3775 } 3776 3777 gclog_or_tty->date_stamp(PrintGCDateStamps); 3778 gclog_or_tty->stamp(PrintGCTimeStamps); 3779 3780 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3781 .append(g1_policy()->gcs_are_young() ? " (young)" : " (mixed)") 3782 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3783 3784 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3785 } 3786 3787 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3788 if (!G1Log::fine()) { 3789 return; 3790 } 3791 3792 if (G1Log::finer()) { 3793 if (evacuation_failed()) { 3794 gclog_or_tty->print(" (to-space exhausted)"); 3795 } 3796 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3797 g1_policy()->phase_times()->note_gc_end(); 3798 g1_policy()->phase_times()->print(pause_time_sec); 3799 g1_policy()->print_detailed_heap_transition(); 3800 } else { 3801 if (evacuation_failed()) { 3802 gclog_or_tty->print("--"); 3803 } 3804 g1_policy()->print_heap_transition(); 3805 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3806 } 3807 gclog_or_tty->flush(); 3808 } 3809 3810 bool 3811 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3812 assert_at_safepoint(true /* should_be_vm_thread */); 3813 guarantee(!is_gc_active(), "collection is not reentrant"); 3814 3815 if (GC_locker::check_active_before_gc()) { 3816 return false; 3817 } 3818 3819 _gc_timer_stw->register_gc_start(os::elapsed_counter()); 3820 3821 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3822 3823 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3824 ResourceMark rm; 3825 3826 print_heap_before_gc(); 3827 trace_heap_before_gc(_gc_tracer_stw); 3828 3829 HRSPhaseSetter x(HRSPhaseEvacuation); 3830 verify_region_sets_optional(); 3831 verify_dirty_young_regions(); 3832 3833 // This call will decide whether this pause is an initial-mark 3834 // pause. If it is, during_initial_mark_pause() will return true 3835 // for the duration of this pause. 3836 g1_policy()->decide_on_conc_mark_initiation(); 3837 3838 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3839 assert(!g1_policy()->during_initial_mark_pause() || 3840 g1_policy()->gcs_are_young(), "sanity"); 3841 3842 // We also do not allow mixed GCs during marking. 3843 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3844 3845 // Record whether this pause is an initial mark. When the current 3846 // thread has completed its logging output and it's safe to signal 3847 // the CM thread, the flag's value in the policy has been reset. 3848 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3849 3850 // Inner scope for scope based logging, timers, and stats collection 3851 { 3852 EvacuationInfo evacuation_info; 3853 3854 if (g1_policy()->during_initial_mark_pause()) { 3855 // We are about to start a marking cycle, so we increment the 3856 // full collection counter. 3857 increment_old_marking_cycles_started(); 3858 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3859 } 3860 3861 _gc_tracer_stw->report_yc_type(yc_type()); 3862 3863 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3864 3865 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3866 workers()->active_workers() : 1); 3867 double pause_start_sec = os::elapsedTime(); 3868 g1_policy()->phase_times()->note_gc_start(active_workers); 3869 log_gc_header(); 3870 3871 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3872 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3873 3874 // If the secondary_free_list is not empty, append it to the 3875 // free_list. No need to wait for the cleanup operation to finish; 3876 // the region allocation code will check the secondary_free_list 3877 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3878 // set, skip this step so that the region allocation code has to 3879 // get entries from the secondary_free_list. 3880 if (!G1StressConcRegionFreeing) { 3881 append_secondary_free_list_if_not_empty_with_lock(); 3882 } 3883 3884 assert(check_young_list_well_formed(), 3885 "young list should be well formed"); 3886 3887 // Don't dynamically change the number of GC threads this early. A value of 3888 // 0 is used to indicate serial work. When parallel work is done, 3889 // it will be set. 3890 3891 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3892 IsGCActiveMark x; 3893 3894 gc_prologue(false); 3895 increment_total_collections(false /* full gc */); 3896 increment_gc_time_stamp(); 3897 3898 verify_before_gc(); 3899 3900 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3901 3902 // Please see comment in g1CollectedHeap.hpp and 3903 // G1CollectedHeap::ref_processing_init() to see how 3904 // reference processing currently works in G1. 3905 3906 // Enable discovery in the STW reference processor 3907 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3908 true /*verify_no_refs*/); 3909 3910 { 3911 // We want to temporarily turn off discovery by the 3912 // CM ref processor, if necessary, and turn it back on 3913 // on again later if we do. Using a scoped 3914 // NoRefDiscovery object will do this. 3915 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3916 3917 // Forget the current alloc region (we might even choose it to be part 3918 // of the collection set!). 3919 release_mutator_alloc_region(); 3920 3921 // We should call this after we retire the mutator alloc 3922 // region(s) so that all the ALLOC / RETIRE events are generated 3923 // before the start GC event. 3924 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3925 3926 // This timing is only used by the ergonomics to handle our pause target. 3927 // It is unclear why this should not include the full pause. We will 3928 // investigate this in CR 7178365. 3929 // 3930 // Preserving the old comment here if that helps the investigation: 3931 // 3932 // The elapsed time induced by the start time below deliberately elides 3933 // the possible verification above. 3934 double sample_start_time_sec = os::elapsedTime(); 3935 3936 #if YOUNG_LIST_VERBOSE 3937 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3938 _young_list->print(); 3939 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3940 #endif // YOUNG_LIST_VERBOSE 3941 3942 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3943 3944 double scan_wait_start = os::elapsedTime(); 3945 // We have to wait until the CM threads finish scanning the 3946 // root regions as it's the only way to ensure that all the 3947 // objects on them have been correctly scanned before we start 3948 // moving them during the GC. 3949 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3950 double wait_time_ms = 0.0; 3951 if (waited) { 3952 double scan_wait_end = os::elapsedTime(); 3953 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3954 } 3955 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3956 3957 #if YOUNG_LIST_VERBOSE 3958 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3959 _young_list->print(); 3960 #endif // YOUNG_LIST_VERBOSE 3961 3962 if (g1_policy()->during_initial_mark_pause()) { 3963 concurrent_mark()->checkpointRootsInitialPre(); 3964 } 3965 perm_gen()->save_marks(); 3966 3967 #if YOUNG_LIST_VERBOSE 3968 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3969 _young_list->print(); 3970 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3971 #endif // YOUNG_LIST_VERBOSE 3972 3973 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3974 3975 _cm->note_start_of_gc(); 3976 // We should not verify the per-thread SATB buffers given that 3977 // we have not filtered them yet (we'll do so during the 3978 // GC). We also call this after finalize_cset() to 3979 // ensure that the CSet has been finalized. 3980 _cm->verify_no_cset_oops(true /* verify_stacks */, 3981 true /* verify_enqueued_buffers */, 3982 false /* verify_thread_buffers */, 3983 true /* verify_fingers */); 3984 3985 if (_hr_printer.is_active()) { 3986 HeapRegion* hr = g1_policy()->collection_set(); 3987 while (hr != NULL) { 3988 G1HRPrinter::RegionType type; 3989 if (!hr->is_young()) { 3990 type = G1HRPrinter::Old; 3991 } else if (hr->is_survivor()) { 3992 type = G1HRPrinter::Survivor; 3993 } else { 3994 type = G1HRPrinter::Eden; 3995 } 3996 _hr_printer.cset(hr); 3997 hr = hr->next_in_collection_set(); 3998 } 3999 } 4000 4001 #ifdef ASSERT 4002 VerifyCSetClosure cl; 4003 collection_set_iterate(&cl); 4004 #endif // ASSERT 4005 4006 setup_surviving_young_words(); 4007 4008 // Initialize the GC alloc regions. 4009 init_gc_alloc_regions(evacuation_info); 4010 4011 // Actually do the work... 4012 evacuate_collection_set(evacuation_info); 4013 4014 // We do this to mainly verify the per-thread SATB buffers 4015 // (which have been filtered by now) since we didn't verify 4016 // them earlier. No point in re-checking the stacks / enqueued 4017 // buffers given that the CSet has not changed since last time 4018 // we checked. 4019 _cm->verify_no_cset_oops(false /* verify_stacks */, 4020 false /* verify_enqueued_buffers */, 4021 true /* verify_thread_buffers */, 4022 true /* verify_fingers */); 4023 4024 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4025 g1_policy()->clear_collection_set(); 4026 4027 cleanup_surviving_young_words(); 4028 4029 // Start a new incremental collection set for the next pause. 4030 g1_policy()->start_incremental_cset_building(); 4031 4032 // Clear the _cset_fast_test bitmap in anticipation of adding 4033 // regions to the incremental collection set for the next 4034 // evacuation pause. 4035 clear_cset_fast_test(); 4036 4037 _young_list->reset_sampled_info(); 4038 4039 // Don't check the whole heap at this point as the 4040 // GC alloc regions from this pause have been tagged 4041 // as survivors and moved on to the survivor list. 4042 // Survivor regions will fail the !is_young() check. 4043 assert(check_young_list_empty(false /* check_heap */), 4044 "young list should be empty"); 4045 4046 #if YOUNG_LIST_VERBOSE 4047 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4048 _young_list->print(); 4049 #endif // YOUNG_LIST_VERBOSE 4050 4051 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4052 _young_list->first_survivor_region(), 4053 _young_list->last_survivor_region()); 4054 4055 _young_list->reset_auxilary_lists(); 4056 4057 if (evacuation_failed()) { 4058 _summary_bytes_used = recalculate_used(); 4059 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4060 for (uint i = 0; i < n_queues; i++) { 4061 if (_evacuation_failed_info_array[i].has_failed()) { 4062 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4063 } 4064 } 4065 } else { 4066 // The "used" of the the collection set have already been subtracted 4067 // when they were freed. Add in the bytes evacuated. 4068 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4069 } 4070 4071 if (g1_policy()->during_initial_mark_pause()) { 4072 // We have to do this before we notify the CM threads that 4073 // they can start working to make sure that all the 4074 // appropriate initialization is done on the CM object. 4075 concurrent_mark()->checkpointRootsInitialPost(); 4076 set_marking_started(); 4077 // Note that we don't actually trigger the CM thread at 4078 // this point. We do that later when we're sure that 4079 // the current thread has completed its logging output. 4080 } 4081 4082 allocate_dummy_regions(); 4083 4084 #if YOUNG_LIST_VERBOSE 4085 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4086 _young_list->print(); 4087 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4088 #endif // YOUNG_LIST_VERBOSE 4089 4090 init_mutator_alloc_region(); 4091 4092 { 4093 size_t expand_bytes = g1_policy()->expansion_amount(); 4094 if (expand_bytes > 0) { 4095 size_t bytes_before = capacity(); 4096 // No need for an ergo verbose message here, 4097 // expansion_amount() does this when it returns a value > 0. 4098 if (!expand(expand_bytes)) { 4099 // We failed to expand the heap so let's verify that 4100 // committed/uncommitted amount match the backing store 4101 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4102 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4103 } 4104 } 4105 } 4106 4107 // We redo the verification but now wrt to the new CSet which 4108 // has just got initialized after the previous CSet was freed. 4109 _cm->verify_no_cset_oops(true /* verify_stacks */, 4110 true /* verify_enqueued_buffers */, 4111 true /* verify_thread_buffers */, 4112 true /* verify_fingers */); 4113 _cm->note_end_of_gc(); 4114 4115 // This timing is only used by the ergonomics to handle our pause target. 4116 // It is unclear why this should not include the full pause. We will 4117 // investigate this in CR 7178365. 4118 double sample_end_time_sec = os::elapsedTime(); 4119 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4120 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4121 4122 MemoryService::track_memory_usage(); 4123 4124 // In prepare_for_verify() below we'll need to scan the deferred 4125 // update buffers to bring the RSets up-to-date if 4126 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4127 // the update buffers we'll probably need to scan cards on the 4128 // regions we just allocated to (i.e., the GC alloc 4129 // regions). However, during the last GC we called 4130 // set_saved_mark() on all the GC alloc regions, so card 4131 // scanning might skip the [saved_mark_word()...top()] area of 4132 // those regions (i.e., the area we allocated objects into 4133 // during the last GC). But it shouldn't. Given that 4134 // saved_mark_word() is conditional on whether the GC time stamp 4135 // on the region is current or not, by incrementing the GC time 4136 // stamp here we invalidate all the GC time stamps on all the 4137 // regions and saved_mark_word() will simply return top() for 4138 // all the regions. This is a nicer way of ensuring this rather 4139 // than iterating over the regions and fixing them. In fact, the 4140 // GC time stamp increment here also ensures that 4141 // saved_mark_word() will return top() between pauses, i.e., 4142 // during concurrent refinement. So we don't need the 4143 // is_gc_active() check to decided which top to use when 4144 // scanning cards (see CR 7039627). 4145 increment_gc_time_stamp(); 4146 4147 verify_after_gc(); 4148 4149 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4150 ref_processor_stw()->verify_no_references_recorded(); 4151 4152 // CM reference discovery will be re-enabled if necessary. 4153 } 4154 4155 // We should do this after we potentially expand the heap so 4156 // that all the COMMIT events are generated before the end GC 4157 // event, and after we retire the GC alloc regions so that all 4158 // RETIRE events are generated before the end GC event. 4159 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4160 4161 if (mark_in_progress()) { 4162 concurrent_mark()->update_g1_committed(); 4163 } 4164 4165 #ifdef TRACESPINNING 4166 ParallelTaskTerminator::print_termination_counts(); 4167 #endif 4168 4169 gc_epilogue(false); 4170 } 4171 4172 // Print the remainder of the GC log output. 4173 log_gc_footer(os::elapsedTime() - pause_start_sec); 4174 4175 // It is not yet to safe to tell the concurrent mark to 4176 // start as we have some optional output below. We don't want the 4177 // output from the concurrent mark thread interfering with this 4178 // logging output either. 4179 4180 _hrs.verify_optional(); 4181 verify_region_sets_optional(); 4182 4183 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4184 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4185 4186 print_heap_after_gc(); 4187 trace_heap_after_gc(_gc_tracer_stw); 4188 4189 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4190 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4191 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4192 // before any GC notifications are raised. 4193 g1mm()->update_sizes(); 4194 4195 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4196 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4197 _gc_timer_stw->register_gc_end(os::elapsed_counter()); 4198 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4199 } 4200 4201 if (G1SummarizeRSetStats && 4202 (G1SummarizeRSetStatsPeriod > 0) && 4203 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 4204 g1_rem_set()->print_summary_info(); 4205 } 4206 // It should now be safe to tell the concurrent mark thread to start 4207 // without its logging output interfering with the logging output 4208 // that came from the pause. 4209 4210 if (should_start_conc_mark) { 4211 // CAUTION: after the doConcurrentMark() call below, 4212 // the concurrent marking thread(s) could be running 4213 // concurrently with us. Make sure that anything after 4214 // this point does not assume that we are the only GC thread 4215 // running. Note: of course, the actual marking work will 4216 // not start until the safepoint itself is released in 4217 // ConcurrentGCThread::safepoint_desynchronize(). 4218 doConcurrentMark(); 4219 } 4220 4221 return true; 4222 } 4223 4224 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4225 { 4226 size_t gclab_word_size; 4227 switch (purpose) { 4228 case GCAllocForSurvived: 4229 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4230 break; 4231 case GCAllocForTenured: 4232 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4233 break; 4234 default: 4235 assert(false, "unknown GCAllocPurpose"); 4236 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4237 break; 4238 } 4239 4240 // Prevent humongous PLAB sizes for two reasons: 4241 // * PLABs are allocated using a similar paths as oops, but should 4242 // never be in a humongous region 4243 // * Allowing humongous PLABs needlessly churns the region free lists 4244 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4245 } 4246 4247 void G1CollectedHeap::init_mutator_alloc_region() { 4248 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4249 _mutator_alloc_region.init(); 4250 } 4251 4252 void G1CollectedHeap::release_mutator_alloc_region() { 4253 _mutator_alloc_region.release(); 4254 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4255 } 4256 4257 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4258 assert_at_safepoint(true /* should_be_vm_thread */); 4259 4260 _survivor_gc_alloc_region.init(); 4261 _old_gc_alloc_region.init(); 4262 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4263 _retained_old_gc_alloc_region = NULL; 4264 4265 // We will discard the current GC alloc region if: 4266 // a) it's in the collection set (it can happen!), 4267 // b) it's already full (no point in using it), 4268 // c) it's empty (this means that it was emptied during 4269 // a cleanup and it should be on the free list now), or 4270 // d) it's humongous (this means that it was emptied 4271 // during a cleanup and was added to the free list, but 4272 // has been subsequently used to allocate a humongous 4273 // object that may be less than the region size). 4274 if (retained_region != NULL && 4275 !retained_region->in_collection_set() && 4276 !(retained_region->top() == retained_region->end()) && 4277 !retained_region->is_empty() && 4278 !retained_region->isHumongous()) { 4279 retained_region->set_saved_mark(); 4280 // The retained region was added to the old region set when it was 4281 // retired. We have to remove it now, since we don't allow regions 4282 // we allocate to in the region sets. We'll re-add it later, when 4283 // it's retired again. 4284 _old_set.remove(retained_region); 4285 bool during_im = g1_policy()->during_initial_mark_pause(); 4286 retained_region->note_start_of_copying(during_im); 4287 _old_gc_alloc_region.set(retained_region); 4288 _hr_printer.reuse(retained_region); 4289 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4290 } 4291 } 4292 4293 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4294 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4295 _old_gc_alloc_region.count()); 4296 _survivor_gc_alloc_region.release(); 4297 // If we have an old GC alloc region to release, we'll save it in 4298 // _retained_old_gc_alloc_region. If we don't 4299 // _retained_old_gc_alloc_region will become NULL. This is what we 4300 // want either way so no reason to check explicitly for either 4301 // condition. 4302 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4303 4304 if (ResizePLAB) { 4305 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4306 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4307 } 4308 } 4309 4310 void G1CollectedHeap::abandon_gc_alloc_regions() { 4311 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4312 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4313 _retained_old_gc_alloc_region = NULL; 4314 } 4315 4316 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4317 _drain_in_progress = false; 4318 set_evac_failure_closure(cl); 4319 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4320 } 4321 4322 void G1CollectedHeap::finalize_for_evac_failure() { 4323 assert(_evac_failure_scan_stack != NULL && 4324 _evac_failure_scan_stack->length() == 0, 4325 "Postcondition"); 4326 assert(!_drain_in_progress, "Postcondition"); 4327 delete _evac_failure_scan_stack; 4328 _evac_failure_scan_stack = NULL; 4329 } 4330 4331 void G1CollectedHeap::remove_self_forwarding_pointers() { 4332 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4333 4334 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4335 4336 if (G1CollectedHeap::use_parallel_gc_threads()) { 4337 set_par_threads(); 4338 workers()->run_task(&rsfp_task); 4339 set_par_threads(0); 4340 } else { 4341 rsfp_task.work(0); 4342 } 4343 4344 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4345 4346 // Reset the claim values in the regions in the collection set. 4347 reset_cset_heap_region_claim_values(); 4348 4349 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4350 4351 // Now restore saved marks, if any. 4352 assert(_objs_with_preserved_marks.size() == 4353 _preserved_marks_of_objs.size(), "Both or none."); 4354 while (!_objs_with_preserved_marks.is_empty()) { 4355 oop obj = _objs_with_preserved_marks.pop(); 4356 markOop m = _preserved_marks_of_objs.pop(); 4357 obj->set_mark(m); 4358 } 4359 _objs_with_preserved_marks.clear(true); 4360 _preserved_marks_of_objs.clear(true); 4361 } 4362 4363 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4364 _evac_failure_scan_stack->push(obj); 4365 } 4366 4367 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4368 assert(_evac_failure_scan_stack != NULL, "precondition"); 4369 4370 while (_evac_failure_scan_stack->length() > 0) { 4371 oop obj = _evac_failure_scan_stack->pop(); 4372 _evac_failure_closure->set_region(heap_region_containing(obj)); 4373 obj->oop_iterate_backwards(_evac_failure_closure); 4374 } 4375 } 4376 4377 oop 4378 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4379 oop old) { 4380 assert(obj_in_cs(old), 4381 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4382 (HeapWord*) old)); 4383 markOop m = old->mark(); 4384 oop forward_ptr = old->forward_to_atomic(old); 4385 if (forward_ptr == NULL) { 4386 // Forward-to-self succeeded. 4387 assert(_par_scan_state != NULL, "par scan state"); 4388 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4389 uint queue_num = _par_scan_state->queue_num(); 4390 4391 _evacuation_failed = true; 4392 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4393 if (_evac_failure_closure != cl) { 4394 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4395 assert(!_drain_in_progress, 4396 "Should only be true while someone holds the lock."); 4397 // Set the global evac-failure closure to the current thread's. 4398 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4399 set_evac_failure_closure(cl); 4400 // Now do the common part. 4401 handle_evacuation_failure_common(old, m); 4402 // Reset to NULL. 4403 set_evac_failure_closure(NULL); 4404 } else { 4405 // The lock is already held, and this is recursive. 4406 assert(_drain_in_progress, "This should only be the recursive case."); 4407 handle_evacuation_failure_common(old, m); 4408 } 4409 return old; 4410 } else { 4411 // Forward-to-self failed. Either someone else managed to allocate 4412 // space for this object (old != forward_ptr) or they beat us in 4413 // self-forwarding it (old == forward_ptr). 4414 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4415 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4416 "should not be in the CSet", 4417 (HeapWord*) old, (HeapWord*) forward_ptr)); 4418 return forward_ptr; 4419 } 4420 } 4421 4422 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4423 preserve_mark_if_necessary(old, m); 4424 4425 HeapRegion* r = heap_region_containing(old); 4426 if (!r->evacuation_failed()) { 4427 r->set_evacuation_failed(true); 4428 _hr_printer.evac_failure(r); 4429 } 4430 4431 push_on_evac_failure_scan_stack(old); 4432 4433 if (!_drain_in_progress) { 4434 // prevent recursion in copy_to_survivor_space() 4435 _drain_in_progress = true; 4436 drain_evac_failure_scan_stack(); 4437 _drain_in_progress = false; 4438 } 4439 } 4440 4441 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4442 assert(evacuation_failed(), "Oversaving!"); 4443 // We want to call the "for_promotion_failure" version only in the 4444 // case of a promotion failure. 4445 if (m->must_be_preserved_for_promotion_failure(obj)) { 4446 _objs_with_preserved_marks.push(obj); 4447 _preserved_marks_of_objs.push(m); 4448 } 4449 } 4450 4451 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4452 size_t word_size) { 4453 if (purpose == GCAllocForSurvived) { 4454 HeapWord* result = survivor_attempt_allocation(word_size); 4455 if (result != NULL) { 4456 return result; 4457 } else { 4458 // Let's try to allocate in the old gen in case we can fit the 4459 // object there. 4460 return old_attempt_allocation(word_size); 4461 } 4462 } else { 4463 assert(purpose == GCAllocForTenured, "sanity"); 4464 HeapWord* result = old_attempt_allocation(word_size); 4465 if (result != NULL) { 4466 return result; 4467 } else { 4468 // Let's try to allocate in the survivors in case we can fit the 4469 // object there. 4470 return survivor_attempt_allocation(word_size); 4471 } 4472 } 4473 4474 ShouldNotReachHere(); 4475 // Trying to keep some compilers happy. 4476 return NULL; 4477 } 4478 4479 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4480 ParGCAllocBuffer(gclab_word_size), _retired(false) { } 4481 4482 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num) 4483 : _g1h(g1h), 4484 _refs(g1h->task_queue(queue_num)), 4485 _dcq(&g1h->dirty_card_queue_set()), 4486 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()), 4487 _g1_rem(g1h->g1_rem_set()), 4488 _hash_seed(17), _queue_num(queue_num), 4489 _term_attempts(0), 4490 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4491 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4492 _age_table(false), 4493 _strong_roots_time(0), _term_time(0), 4494 _alloc_buffer_waste(0), _undo_waste(0) { 4495 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4496 // we "sacrifice" entry 0 to keep track of surviving bytes for 4497 // non-young regions (where the age is -1) 4498 // We also add a few elements at the beginning and at the end in 4499 // an attempt to eliminate cache contention 4500 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4501 uint array_length = PADDING_ELEM_NUM + 4502 real_length + 4503 PADDING_ELEM_NUM; 4504 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4505 if (_surviving_young_words_base == NULL) 4506 vm_exit_out_of_memory(array_length * sizeof(size_t), 4507 "Not enough space for young surv histo."); 4508 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4509 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4510 4511 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4512 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4513 4514 _start = os::elapsedTime(); 4515 } 4516 4517 void 4518 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4519 { 4520 st->print_raw_cr("GC Termination Stats"); 4521 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4522 " ------waste (KiB)------"); 4523 st->print_raw_cr("thr ms ms % ms % attempts" 4524 " total alloc undo"); 4525 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4526 " ------- ------- -------"); 4527 } 4528 4529 void 4530 G1ParScanThreadState::print_termination_stats(int i, 4531 outputStream* const st) const 4532 { 4533 const double elapsed_ms = elapsed_time() * 1000.0; 4534 const double s_roots_ms = strong_roots_time() * 1000.0; 4535 const double term_ms = term_time() * 1000.0; 4536 st->print_cr("%3d %9.2f %9.2f %6.2f " 4537 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4538 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4539 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4540 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4541 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4542 alloc_buffer_waste() * HeapWordSize / K, 4543 undo_waste() * HeapWordSize / K); 4544 } 4545 4546 #ifdef ASSERT 4547 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4548 assert(ref != NULL, "invariant"); 4549 assert(UseCompressedOops, "sanity"); 4550 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4551 oop p = oopDesc::load_decode_heap_oop(ref); 4552 assert(_g1h->is_in_g1_reserved(p), 4553 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4554 return true; 4555 } 4556 4557 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4558 assert(ref != NULL, "invariant"); 4559 if (has_partial_array_mask(ref)) { 4560 // Must be in the collection set--it's already been copied. 4561 oop p = clear_partial_array_mask(ref); 4562 assert(_g1h->obj_in_cs(p), 4563 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4564 } else { 4565 oop p = oopDesc::load_decode_heap_oop(ref); 4566 assert(_g1h->is_in_g1_reserved(p), 4567 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4568 } 4569 return true; 4570 } 4571 4572 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4573 if (ref.is_narrow()) { 4574 return verify_ref((narrowOop*) ref); 4575 } else { 4576 return verify_ref((oop*) ref); 4577 } 4578 } 4579 #endif // ASSERT 4580 4581 void G1ParScanThreadState::trim_queue() { 4582 assert(_evac_cl != NULL, "not set"); 4583 assert(_evac_failure_cl != NULL, "not set"); 4584 assert(_partial_scan_cl != NULL, "not set"); 4585 4586 StarTask ref; 4587 do { 4588 // Drain the overflow stack first, so other threads can steal. 4589 while (refs()->pop_overflow(ref)) { 4590 deal_with_reference(ref); 4591 } 4592 4593 while (refs()->pop_local(ref)) { 4594 deal_with_reference(ref); 4595 } 4596 } while (!refs()->is_empty()); 4597 } 4598 4599 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4600 G1ParScanThreadState* par_scan_state) : 4601 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()), 4602 _par_scan_state(par_scan_state), 4603 _worker_id(par_scan_state->queue_num()), 4604 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()), 4605 _mark_in_progress(_g1->mark_in_progress()) { } 4606 4607 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4608 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) { 4609 #ifdef ASSERT 4610 HeapRegion* hr = _g1->heap_region_containing(obj); 4611 assert(hr != NULL, "sanity"); 4612 assert(!hr->in_collection_set(), "should not mark objects in the CSet"); 4613 #endif // ASSERT 4614 4615 // We know that the object is not moving so it's safe to read its size. 4616 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4617 } 4618 4619 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4620 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4621 ::mark_forwarded_object(oop from_obj, oop to_obj) { 4622 #ifdef ASSERT 4623 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4624 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4625 assert(from_obj != to_obj, "should not be self-forwarded"); 4626 4627 HeapRegion* from_hr = _g1->heap_region_containing(from_obj); 4628 assert(from_hr != NULL, "sanity"); 4629 assert(from_hr->in_collection_set(), "from obj should be in the CSet"); 4630 4631 HeapRegion* to_hr = _g1->heap_region_containing(to_obj); 4632 assert(to_hr != NULL, "sanity"); 4633 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet"); 4634 #endif // ASSERT 4635 4636 // The object might be in the process of being copied by another 4637 // worker so we cannot trust that its to-space image is 4638 // well-formed. So we have to read its size from its from-space 4639 // image which we know should not be changing. 4640 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4641 } 4642 4643 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4644 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4645 ::copy_to_survivor_space(oop old) { 4646 size_t word_sz = old->size(); 4647 HeapRegion* from_region = _g1->heap_region_containing_raw(old); 4648 // +1 to make the -1 indexes valid... 4649 int young_index = from_region->young_index_in_cset()+1; 4650 assert( (from_region->is_young() && young_index > 0) || 4651 (!from_region->is_young() && young_index == 0), "invariant" ); 4652 G1CollectorPolicy* g1p = _g1->g1_policy(); 4653 markOop m = old->mark(); 4654 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4655 : m->age(); 4656 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4657 word_sz); 4658 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz); 4659 #ifndef PRODUCT 4660 // Should this evacuation fail? 4661 if (_g1->evacuation_should_fail()) { 4662 if (obj_ptr != NULL) { 4663 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4664 obj_ptr = NULL; 4665 } 4666 } 4667 #endif // !PRODUCT 4668 4669 if (obj_ptr == NULL) { 4670 // This will either forward-to-self, or detect that someone else has 4671 // installed a forwarding pointer. 4672 return _g1->handle_evacuation_failure_par(_par_scan_state, old); 4673 } 4674 4675 oop obj = oop(obj_ptr); 4676 4677 // We're going to allocate linearly, so might as well prefetch ahead. 4678 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4679 4680 oop forward_ptr = old->forward_to_atomic(obj); 4681 if (forward_ptr == NULL) { 4682 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4683 if (g1p->track_object_age(alloc_purpose)) { 4684 // We could simply do obj->incr_age(). However, this causes a 4685 // performance issue. obj->incr_age() will first check whether 4686 // the object has a displaced mark by checking its mark word; 4687 // getting the mark word from the new location of the object 4688 // stalls. So, given that we already have the mark word and we 4689 // are about to install it anyway, it's better to increase the 4690 // age on the mark word, when the object does not have a 4691 // displaced mark word. We're not expecting many objects to have 4692 // a displaced marked word, so that case is not optimized 4693 // further (it could be...) and we simply call obj->incr_age(). 4694 4695 if (m->has_displaced_mark_helper()) { 4696 // in this case, we have to install the mark word first, 4697 // otherwise obj looks to be forwarded (the old mark word, 4698 // which contains the forward pointer, was copied) 4699 obj->set_mark(m); 4700 obj->incr_age(); 4701 } else { 4702 m = m->incr_age(); 4703 obj->set_mark(m); 4704 } 4705 _par_scan_state->age_table()->add(obj, word_sz); 4706 } else { 4707 obj->set_mark(m); 4708 } 4709 4710 size_t* surv_young_words = _par_scan_state->surviving_young_words(); 4711 surv_young_words[young_index] += word_sz; 4712 4713 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4714 // We keep track of the next start index in the length field of 4715 // the to-space object. The actual length can be found in the 4716 // length field of the from-space object. 4717 arrayOop(obj)->set_length(0); 4718 oop* old_p = set_partial_array_mask(old); 4719 _par_scan_state->push_on_queue(old_p); 4720 } else { 4721 // No point in using the slower heap_region_containing() method, 4722 // given that we know obj is in the heap. 4723 _scanner.set_region(_g1->heap_region_containing_raw(obj)); 4724 obj->oop_iterate_backwards(&_scanner); 4725 } 4726 } else { 4727 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4728 obj = forward_ptr; 4729 } 4730 return obj; 4731 } 4732 4733 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4734 template <class T> 4735 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4736 ::do_oop_work(T* p) { 4737 oop obj = oopDesc::load_decode_heap_oop(p); 4738 assert(barrier != G1BarrierRS || obj != NULL, 4739 "Precondition: G1BarrierRS implies obj is non-NULL"); 4740 4741 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4742 4743 // here the null check is implicit in the cset_fast_test() test 4744 if (_g1->in_cset_fast_test(obj)) { 4745 oop forwardee; 4746 if (obj->is_forwarded()) { 4747 forwardee = obj->forwardee(); 4748 } else { 4749 forwardee = copy_to_survivor_space(obj); 4750 } 4751 assert(forwardee != NULL, "forwardee should not be NULL"); 4752 oopDesc::encode_store_heap_oop(p, forwardee); 4753 if (do_mark_object && forwardee != obj) { 4754 // If the object is self-forwarded we don't need to explicitly 4755 // mark it, the evacuation failure protocol will do so. 4756 mark_forwarded_object(obj, forwardee); 4757 } 4758 4759 // When scanning the RS, we only care about objs in CS. 4760 if (barrier == G1BarrierRS) { 4761 _par_scan_state->update_rs(_from, p, _worker_id); 4762 } 4763 } else { 4764 // The object is not in collection set. If we're a root scanning 4765 // closure during an initial mark pause (i.e. do_mark_object will 4766 // be true) then attempt to mark the object. 4767 if (do_mark_object && _g1->is_in_g1_reserved(obj)) { 4768 mark_object(obj); 4769 } 4770 } 4771 4772 if (barrier == G1BarrierEvac && obj != NULL) { 4773 _par_scan_state->update_rs(_from, p, _worker_id); 4774 } 4775 4776 if (do_gen_barrier && obj != NULL) { 4777 par_do_barrier(p); 4778 } 4779 } 4780 4781 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p); 4782 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4783 4784 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) { 4785 assert(has_partial_array_mask(p), "invariant"); 4786 oop from_obj = clear_partial_array_mask(p); 4787 4788 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap."); 4789 assert(from_obj->is_objArray(), "must be obj array"); 4790 objArrayOop from_obj_array = objArrayOop(from_obj); 4791 // The from-space object contains the real length. 4792 int length = from_obj_array->length(); 4793 4794 assert(from_obj->is_forwarded(), "must be forwarded"); 4795 oop to_obj = from_obj->forwardee(); 4796 assert(from_obj != to_obj, "should not be chunking self-forwarded objects"); 4797 objArrayOop to_obj_array = objArrayOop(to_obj); 4798 // We keep track of the next start index in the length field of the 4799 // to-space object. 4800 int next_index = to_obj_array->length(); 4801 assert(0 <= next_index && next_index < length, 4802 err_msg("invariant, next index: %d, length: %d", next_index, length)); 4803 4804 int start = next_index; 4805 int end = length; 4806 int remainder = end - start; 4807 // We'll try not to push a range that's smaller than ParGCArrayScanChunk. 4808 if (remainder > 2 * ParGCArrayScanChunk) { 4809 end = start + ParGCArrayScanChunk; 4810 to_obj_array->set_length(end); 4811 // Push the remainder before we process the range in case another 4812 // worker has run out of things to do and can steal it. 4813 oop* from_obj_p = set_partial_array_mask(from_obj); 4814 _par_scan_state->push_on_queue(from_obj_p); 4815 } else { 4816 assert(length == end, "sanity"); 4817 // We'll process the final range for this object. Restore the length 4818 // so that the heap remains parsable in case of evacuation failure. 4819 to_obj_array->set_length(end); 4820 } 4821 _scanner.set_region(_g1->heap_region_containing_raw(to_obj)); 4822 // Process indexes [start,end). It will also process the header 4823 // along with the first chunk (i.e., the chunk with start == 0). 4824 // Note that at this point the length field of to_obj_array is not 4825 // correct given that we are using it to keep track of the next 4826 // start index. oop_iterate_range() (thankfully!) ignores the length 4827 // field and only relies on the start / end parameters. It does 4828 // however return the size of the object which will be incorrect. So 4829 // we have to ignore it even if we wanted to use it. 4830 to_obj_array->oop_iterate_range(&_scanner, start, end); 4831 } 4832 4833 class G1ParEvacuateFollowersClosure : public VoidClosure { 4834 protected: 4835 G1CollectedHeap* _g1h; 4836 G1ParScanThreadState* _par_scan_state; 4837 RefToScanQueueSet* _queues; 4838 ParallelTaskTerminator* _terminator; 4839 4840 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4841 RefToScanQueueSet* queues() { return _queues; } 4842 ParallelTaskTerminator* terminator() { return _terminator; } 4843 4844 public: 4845 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4846 G1ParScanThreadState* par_scan_state, 4847 RefToScanQueueSet* queues, 4848 ParallelTaskTerminator* terminator) 4849 : _g1h(g1h), _par_scan_state(par_scan_state), 4850 _queues(queues), _terminator(terminator) {} 4851 4852 void do_void(); 4853 4854 private: 4855 inline bool offer_termination(); 4856 }; 4857 4858 bool G1ParEvacuateFollowersClosure::offer_termination() { 4859 G1ParScanThreadState* const pss = par_scan_state(); 4860 pss->start_term_time(); 4861 const bool res = terminator()->offer_termination(); 4862 pss->end_term_time(); 4863 return res; 4864 } 4865 4866 void G1ParEvacuateFollowersClosure::do_void() { 4867 StarTask stolen_task; 4868 G1ParScanThreadState* const pss = par_scan_state(); 4869 pss->trim_queue(); 4870 4871 do { 4872 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4873 assert(pss->verify_task(stolen_task), "sanity"); 4874 if (stolen_task.is_narrow()) { 4875 pss->deal_with_reference((narrowOop*) stolen_task); 4876 } else { 4877 pss->deal_with_reference((oop*) stolen_task); 4878 } 4879 4880 // We've just processed a reference and we might have made 4881 // available new entries on the queues. So we have to make sure 4882 // we drain the queues as necessary. 4883 pss->trim_queue(); 4884 } 4885 } while (!offer_termination()); 4886 4887 pss->retire_alloc_buffers(); 4888 } 4889 4890 class G1ParTask : public AbstractGangTask { 4891 protected: 4892 G1CollectedHeap* _g1h; 4893 RefToScanQueueSet *_queues; 4894 ParallelTaskTerminator _terminator; 4895 uint _n_workers; 4896 4897 Mutex _stats_lock; 4898 Mutex* stats_lock() { return &_stats_lock; } 4899 4900 size_t getNCards() { 4901 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4902 / G1BlockOffsetSharedArray::N_bytes; 4903 } 4904 4905 public: 4906 G1ParTask(G1CollectedHeap* g1h, 4907 RefToScanQueueSet *task_queues) 4908 : AbstractGangTask("G1 collection"), 4909 _g1h(g1h), 4910 _queues(task_queues), 4911 _terminator(0, _queues), 4912 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4913 {} 4914 4915 RefToScanQueueSet* queues() { return _queues; } 4916 4917 RefToScanQueue *work_queue(int i) { 4918 return queues()->queue(i); 4919 } 4920 4921 ParallelTaskTerminator* terminator() { return &_terminator; } 4922 4923 virtual void set_for_termination(int active_workers) { 4924 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4925 // in the young space (_par_seq_tasks) in the G1 heap 4926 // for SequentialSubTasksDone. 4927 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4928 // both of which need setting by set_n_termination(). 4929 _g1h->SharedHeap::set_n_termination(active_workers); 4930 _g1h->set_n_termination(active_workers); 4931 terminator()->reset_for_reuse(active_workers); 4932 _n_workers = active_workers; 4933 } 4934 4935 void work(uint worker_id) { 4936 if (worker_id >= _n_workers) return; // no work needed this round 4937 4938 double start_time_ms = os::elapsedTime() * 1000.0; 4939 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4940 4941 { 4942 ResourceMark rm; 4943 HandleMark hm; 4944 4945 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4946 4947 G1ParScanThreadState pss(_g1h, worker_id); 4948 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp); 4949 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4950 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp); 4951 4952 pss.set_evac_closure(&scan_evac_cl); 4953 pss.set_evac_failure_closure(&evac_failure_cl); 4954 pss.set_partial_scan_closure(&partial_scan_cl); 4955 4956 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 4957 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp); 4958 4959 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 4960 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp); 4961 4962 OopClosure* scan_root_cl = &only_scan_root_cl; 4963 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl; 4964 4965 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4966 // We also need to mark copied objects. 4967 scan_root_cl = &scan_mark_root_cl; 4968 scan_perm_cl = &scan_mark_perm_cl; 4969 } 4970 4971 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4972 4973 pss.start_strong_roots(); 4974 _g1h->g1_process_strong_roots(/* not collecting perm */ false, 4975 SharedHeap::SO_AllClasses, 4976 scan_root_cl, 4977 &push_heap_rs_cl, 4978 scan_perm_cl, 4979 worker_id); 4980 pss.end_strong_roots(); 4981 4982 { 4983 double start = os::elapsedTime(); 4984 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4985 evac.do_void(); 4986 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4987 double term_ms = pss.term_time()*1000.0; 4988 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4989 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4990 } 4991 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4992 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4993 4994 if (ParallelGCVerbose) { 4995 MutexLocker x(stats_lock()); 4996 pss.print_termination_stats(worker_id); 4997 } 4998 4999 assert(pss.refs()->is_empty(), "should be empty"); 5000 5001 // Close the inner scope so that the ResourceMark and HandleMark 5002 // destructors are executed here and are included as part of the 5003 // "GC Worker Time". 5004 } 5005 5006 double end_time_ms = os::elapsedTime() * 1000.0; 5007 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 5008 } 5009 }; 5010 5011 // *** Common G1 Evacuation Stuff 5012 5013 // Closures that support the filtering of CodeBlobs scanned during 5014 // external root scanning. 5015 5016 // Closure applied to reference fields in code blobs (specifically nmethods) 5017 // to determine whether an nmethod contains references that point into 5018 // the collection set. Used as a predicate when walking code roots so 5019 // that only nmethods that point into the collection set are added to the 5020 // 'marked' list. 5021 5022 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure { 5023 5024 class G1PointsIntoCSOopClosure : public OopClosure { 5025 G1CollectedHeap* _g1; 5026 bool _points_into_cs; 5027 public: 5028 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) : 5029 _g1(g1), _points_into_cs(false) { } 5030 5031 bool points_into_cs() const { return _points_into_cs; } 5032 5033 template <class T> 5034 void do_oop_nv(T* p) { 5035 if (!_points_into_cs) { 5036 T heap_oop = oopDesc::load_heap_oop(p); 5037 if (!oopDesc::is_null(heap_oop) && 5038 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) { 5039 _points_into_cs = true; 5040 } 5041 } 5042 } 5043 5044 virtual void do_oop(oop* p) { do_oop_nv(p); } 5045 virtual void do_oop(narrowOop* p) { do_oop_nv(p); } 5046 }; 5047 5048 G1CollectedHeap* _g1; 5049 5050 public: 5051 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) : 5052 CodeBlobToOopClosure(cl, true), _g1(g1) { } 5053 5054 virtual void do_code_blob(CodeBlob* cb) { 5055 nmethod* nm = cb->as_nmethod_or_null(); 5056 if (nm != NULL && !(nm->test_oops_do_mark())) { 5057 G1PointsIntoCSOopClosure predicate_cl(_g1); 5058 nm->oops_do(&predicate_cl); 5059 5060 if (predicate_cl.points_into_cs()) { 5061 // At least one of the reference fields or the oop relocations 5062 // in the nmethod points into the collection set. We have to 5063 // 'mark' this nmethod. 5064 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob() 5065 // or MarkingCodeBlobClosure::do_code_blob() change. 5066 if (!nm->test_set_oops_do_mark()) { 5067 do_newly_marked_nmethod(nm); 5068 } 5069 } 5070 } 5071 } 5072 }; 5073 5074 // This method is run in a GC worker. 5075 5076 void 5077 G1CollectedHeap:: 5078 g1_process_strong_roots(bool collecting_perm_gen, 5079 ScanningOption so, 5080 OopClosure* scan_non_heap_roots, 5081 OopsInHeapRegionClosure* scan_rs, 5082 OopsInGenClosure* scan_perm, 5083 int worker_i) { 5084 5085 // First scan the strong roots, including the perm gen. 5086 double ext_roots_start = os::elapsedTime(); 5087 double closure_app_time_sec = 0.0; 5088 5089 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5090 BufferingOopsInGenClosure buf_scan_perm(scan_perm); 5091 buf_scan_perm.set_generation(perm_gen()); 5092 5093 // Walk the code cache w/o buffering, because StarTask cannot handle 5094 // unaligned oop locations. 5095 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots); 5096 5097 process_strong_roots(false, // no scoping; this is parallel code 5098 collecting_perm_gen, so, 5099 &buf_scan_non_heap_roots, 5100 &eager_scan_code_roots, 5101 &buf_scan_perm); 5102 5103 // Now the CM ref_processor roots. 5104 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5105 // We need to treat the discovered reference lists of the 5106 // concurrent mark ref processor as roots and keep entries 5107 // (which are added by the marking threads) on them live 5108 // until they can be processed at the end of marking. 5109 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5110 } 5111 5112 // Finish up any enqueued closure apps (attributed as object copy time). 5113 buf_scan_non_heap_roots.done(); 5114 buf_scan_perm.done(); 5115 5116 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() + 5117 buf_scan_non_heap_roots.closure_app_seconds(); 5118 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5119 5120 double ext_root_time_ms = 5121 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5122 5123 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5124 5125 // During conc marking we have to filter the per-thread SATB buffers 5126 // to make sure we remove any oops into the CSet (which will show up 5127 // as implicitly live). 5128 double satb_filtering_ms = 0.0; 5129 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5130 if (mark_in_progress()) { 5131 double satb_filter_start = os::elapsedTime(); 5132 5133 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5134 5135 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5136 } 5137 } 5138 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5139 5140 // Now scan the complement of the collection set. 5141 if (scan_rs != NULL) { 5142 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i); 5143 } 5144 5145 _process_strong_tasks->all_tasks_completed(); 5146 } 5147 5148 void 5149 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure, 5150 OopClosure* non_root_closure) { 5151 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false); 5152 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure); 5153 } 5154 5155 // Weak Reference Processing support 5156 5157 // An always "is_alive" closure that is used to preserve referents. 5158 // If the object is non-null then it's alive. Used in the preservation 5159 // of referent objects that are pointed to by reference objects 5160 // discovered by the CM ref processor. 5161 class G1AlwaysAliveClosure: public BoolObjectClosure { 5162 G1CollectedHeap* _g1; 5163 public: 5164 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5165 void do_object(oop p) { assert(false, "Do not call."); } 5166 bool do_object_b(oop p) { 5167 if (p != NULL) { 5168 return true; 5169 } 5170 return false; 5171 } 5172 }; 5173 5174 bool G1STWIsAliveClosure::do_object_b(oop p) { 5175 // An object is reachable if it is outside the collection set, 5176 // or is inside and copied. 5177 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5178 } 5179 5180 // Non Copying Keep Alive closure 5181 class G1KeepAliveClosure: public OopClosure { 5182 G1CollectedHeap* _g1; 5183 public: 5184 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5185 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5186 void do_oop( oop* p) { 5187 oop obj = *p; 5188 5189 if (_g1->obj_in_cs(obj)) { 5190 assert( obj->is_forwarded(), "invariant" ); 5191 *p = obj->forwardee(); 5192 } 5193 } 5194 }; 5195 5196 // Copying Keep Alive closure - can be called from both 5197 // serial and parallel code as long as different worker 5198 // threads utilize different G1ParScanThreadState instances 5199 // and different queues. 5200 5201 class G1CopyingKeepAliveClosure: public OopClosure { 5202 G1CollectedHeap* _g1h; 5203 OopClosure* _copy_non_heap_obj_cl; 5204 OopsInHeapRegionClosure* _copy_perm_obj_cl; 5205 G1ParScanThreadState* _par_scan_state; 5206 5207 public: 5208 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5209 OopClosure* non_heap_obj_cl, 5210 OopsInHeapRegionClosure* perm_obj_cl, 5211 G1ParScanThreadState* pss): 5212 _g1h(g1h), 5213 _copy_non_heap_obj_cl(non_heap_obj_cl), 5214 _copy_perm_obj_cl(perm_obj_cl), 5215 _par_scan_state(pss) 5216 {} 5217 5218 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5219 virtual void do_oop( oop* p) { do_oop_work(p); } 5220 5221 template <class T> void do_oop_work(T* p) { 5222 oop obj = oopDesc::load_decode_heap_oop(p); 5223 5224 if (_g1h->obj_in_cs(obj)) { 5225 // If the referent object has been forwarded (either copied 5226 // to a new location or to itself in the event of an 5227 // evacuation failure) then we need to update the reference 5228 // field and, if both reference and referent are in the G1 5229 // heap, update the RSet for the referent. 5230 // 5231 // If the referent has not been forwarded then we have to keep 5232 // it alive by policy. Therefore we have copy the referent. 5233 // 5234 // If the reference field is in the G1 heap then we can push 5235 // on the PSS queue. When the queue is drained (after each 5236 // phase of reference processing) the object and it's followers 5237 // will be copied, the reference field set to point to the 5238 // new location, and the RSet updated. Otherwise we need to 5239 // use the the non-heap or perm closures directly to copy 5240 // the referent object and update the pointer, while avoiding 5241 // updating the RSet. 5242 5243 if (_g1h->is_in_g1_reserved(p)) { 5244 _par_scan_state->push_on_queue(p); 5245 } else { 5246 // The reference field is not in the G1 heap. 5247 if (_g1h->perm_gen()->is_in(p)) { 5248 _copy_perm_obj_cl->do_oop(p); 5249 } else { 5250 _copy_non_heap_obj_cl->do_oop(p); 5251 } 5252 } 5253 } 5254 } 5255 }; 5256 5257 // Serial drain queue closure. Called as the 'complete_gc' 5258 // closure for each discovered list in some of the 5259 // reference processing phases. 5260 5261 class G1STWDrainQueueClosure: public VoidClosure { 5262 protected: 5263 G1CollectedHeap* _g1h; 5264 G1ParScanThreadState* _par_scan_state; 5265 5266 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5267 5268 public: 5269 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5270 _g1h(g1h), 5271 _par_scan_state(pss) 5272 { } 5273 5274 void do_void() { 5275 G1ParScanThreadState* const pss = par_scan_state(); 5276 pss->trim_queue(); 5277 } 5278 }; 5279 5280 // Parallel Reference Processing closures 5281 5282 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5283 // processing during G1 evacuation pauses. 5284 5285 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5286 private: 5287 G1CollectedHeap* _g1h; 5288 RefToScanQueueSet* _queues; 5289 FlexibleWorkGang* _workers; 5290 int _active_workers; 5291 5292 public: 5293 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5294 FlexibleWorkGang* workers, 5295 RefToScanQueueSet *task_queues, 5296 int n_workers) : 5297 _g1h(g1h), 5298 _queues(task_queues), 5299 _workers(workers), 5300 _active_workers(n_workers) 5301 { 5302 assert(n_workers > 0, "shouldn't call this otherwise"); 5303 } 5304 5305 // Executes the given task using concurrent marking worker threads. 5306 virtual void execute(ProcessTask& task); 5307 virtual void execute(EnqueueTask& task); 5308 }; 5309 5310 // Gang task for possibly parallel reference processing 5311 5312 class G1STWRefProcTaskProxy: public AbstractGangTask { 5313 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5314 ProcessTask& _proc_task; 5315 G1CollectedHeap* _g1h; 5316 RefToScanQueueSet *_task_queues; 5317 ParallelTaskTerminator* _terminator; 5318 5319 public: 5320 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5321 G1CollectedHeap* g1h, 5322 RefToScanQueueSet *task_queues, 5323 ParallelTaskTerminator* terminator) : 5324 AbstractGangTask("Process reference objects in parallel"), 5325 _proc_task(proc_task), 5326 _g1h(g1h), 5327 _task_queues(task_queues), 5328 _terminator(terminator) 5329 {} 5330 5331 virtual void work(uint worker_id) { 5332 // The reference processing task executed by a single worker. 5333 ResourceMark rm; 5334 HandleMark hm; 5335 5336 G1STWIsAliveClosure is_alive(_g1h); 5337 5338 G1ParScanThreadState pss(_g1h, worker_id); 5339 5340 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5341 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5342 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5343 5344 pss.set_evac_closure(&scan_evac_cl); 5345 pss.set_evac_failure_closure(&evac_failure_cl); 5346 pss.set_partial_scan_closure(&partial_scan_cl); 5347 5348 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5349 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL); 5350 5351 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5352 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL); 5353 5354 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5355 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl; 5356 5357 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5358 // We also need to mark copied objects. 5359 copy_non_heap_cl = ©_mark_non_heap_cl; 5360 copy_perm_cl = ©_mark_perm_cl; 5361 } 5362 5363 // Keep alive closure. 5364 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss); 5365 5366 // Complete GC closure 5367 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5368 5369 // Call the reference processing task's work routine. 5370 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5371 5372 // Note we cannot assert that the refs array is empty here as not all 5373 // of the processing tasks (specifically phase2 - pp2_work) execute 5374 // the complete_gc closure (which ordinarily would drain the queue) so 5375 // the queue may not be empty. 5376 } 5377 }; 5378 5379 // Driver routine for parallel reference processing. 5380 // Creates an instance of the ref processing gang 5381 // task and has the worker threads execute it. 5382 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5383 assert(_workers != NULL, "Need parallel worker threads."); 5384 5385 ParallelTaskTerminator terminator(_active_workers, _queues); 5386 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5387 5388 _g1h->set_par_threads(_active_workers); 5389 _workers->run_task(&proc_task_proxy); 5390 _g1h->set_par_threads(0); 5391 } 5392 5393 // Gang task for parallel reference enqueueing. 5394 5395 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5396 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5397 EnqueueTask& _enq_task; 5398 5399 public: 5400 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5401 AbstractGangTask("Enqueue reference objects in parallel"), 5402 _enq_task(enq_task) 5403 { } 5404 5405 virtual void work(uint worker_id) { 5406 _enq_task.work(worker_id); 5407 } 5408 }; 5409 5410 // Driver routine for parallel reference enqueueing. 5411 // Creates an instance of the ref enqueueing gang 5412 // task and has the worker threads execute it. 5413 5414 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5415 assert(_workers != NULL, "Need parallel worker threads."); 5416 5417 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5418 5419 _g1h->set_par_threads(_active_workers); 5420 _workers->run_task(&enq_task_proxy); 5421 _g1h->set_par_threads(0); 5422 } 5423 5424 // End of weak reference support closures 5425 5426 // Abstract task used to preserve (i.e. copy) any referent objects 5427 // that are in the collection set and are pointed to by reference 5428 // objects discovered by the CM ref processor. 5429 5430 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5431 protected: 5432 G1CollectedHeap* _g1h; 5433 RefToScanQueueSet *_queues; 5434 ParallelTaskTerminator _terminator; 5435 uint _n_workers; 5436 5437 public: 5438 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5439 AbstractGangTask("ParPreserveCMReferents"), 5440 _g1h(g1h), 5441 _queues(task_queues), 5442 _terminator(workers, _queues), 5443 _n_workers(workers) 5444 { } 5445 5446 void work(uint worker_id) { 5447 ResourceMark rm; 5448 HandleMark hm; 5449 5450 G1ParScanThreadState pss(_g1h, worker_id); 5451 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5452 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5453 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5454 5455 pss.set_evac_closure(&scan_evac_cl); 5456 pss.set_evac_failure_closure(&evac_failure_cl); 5457 pss.set_partial_scan_closure(&partial_scan_cl); 5458 5459 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5460 5461 5462 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5463 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL); 5464 5465 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5466 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL); 5467 5468 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5469 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl; 5470 5471 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5472 // We also need to mark copied objects. 5473 copy_non_heap_cl = ©_mark_non_heap_cl; 5474 copy_perm_cl = ©_mark_perm_cl; 5475 } 5476 5477 // Is alive closure 5478 G1AlwaysAliveClosure always_alive(_g1h); 5479 5480 // Copying keep alive closure. Applied to referent objects that need 5481 // to be copied. 5482 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss); 5483 5484 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5485 5486 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5487 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5488 5489 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5490 // So this must be true - but assert just in case someone decides to 5491 // change the worker ids. 5492 assert(0 <= worker_id && worker_id < limit, "sanity"); 5493 assert(!rp->discovery_is_atomic(), "check this code"); 5494 5495 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5496 for (uint idx = worker_id; idx < limit; idx += stride) { 5497 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5498 5499 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5500 while (iter.has_next()) { 5501 // Since discovery is not atomic for the CM ref processor, we 5502 // can see some null referent objects. 5503 iter.load_ptrs(DEBUG_ONLY(true)); 5504 oop ref = iter.obj(); 5505 5506 // This will filter nulls. 5507 if (iter.is_referent_alive()) { 5508 iter.make_referent_alive(); 5509 } 5510 iter.move_to_next(); 5511 } 5512 } 5513 5514 // Drain the queue - which may cause stealing 5515 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5516 drain_queue.do_void(); 5517 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5518 assert(pss.refs()->is_empty(), "should be"); 5519 } 5520 }; 5521 5522 // Weak Reference processing during an evacuation pause (part 1). 5523 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5524 double ref_proc_start = os::elapsedTime(); 5525 5526 ReferenceProcessor* rp = _ref_processor_stw; 5527 assert(rp->discovery_enabled(), "should have been enabled"); 5528 5529 // Any reference objects, in the collection set, that were 'discovered' 5530 // by the CM ref processor should have already been copied (either by 5531 // applying the external root copy closure to the discovered lists, or 5532 // by following an RSet entry). 5533 // 5534 // But some of the referents, that are in the collection set, that these 5535 // reference objects point to may not have been copied: the STW ref 5536 // processor would have seen that the reference object had already 5537 // been 'discovered' and would have skipped discovering the reference, 5538 // but would not have treated the reference object as a regular oop. 5539 // As a result the copy closure would not have been applied to the 5540 // referent object. 5541 // 5542 // We need to explicitly copy these referent objects - the references 5543 // will be processed at the end of remarking. 5544 // 5545 // We also need to do this copying before we process the reference 5546 // objects discovered by the STW ref processor in case one of these 5547 // referents points to another object which is also referenced by an 5548 // object discovered by the STW ref processor. 5549 5550 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5551 no_of_gc_workers == workers()->active_workers(), 5552 "Need to reset active GC workers"); 5553 5554 set_par_threads(no_of_gc_workers); 5555 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5556 no_of_gc_workers, 5557 _task_queues); 5558 5559 if (G1CollectedHeap::use_parallel_gc_threads()) { 5560 workers()->run_task(&keep_cm_referents); 5561 } else { 5562 keep_cm_referents.work(0); 5563 } 5564 5565 set_par_threads(0); 5566 5567 // Closure to test whether a referent is alive. 5568 G1STWIsAliveClosure is_alive(this); 5569 5570 // Even when parallel reference processing is enabled, the processing 5571 // of JNI refs is serial and performed serially by the current thread 5572 // rather than by a worker. The following PSS will be used for processing 5573 // JNI refs. 5574 5575 // Use only a single queue for this PSS. 5576 G1ParScanThreadState pss(this, 0); 5577 5578 // We do not embed a reference processor in the copying/scanning 5579 // closures while we're actually processing the discovered 5580 // reference objects. 5581 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL); 5582 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5583 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL); 5584 5585 pss.set_evac_closure(&scan_evac_cl); 5586 pss.set_evac_failure_closure(&evac_failure_cl); 5587 pss.set_partial_scan_closure(&partial_scan_cl); 5588 5589 assert(pss.refs()->is_empty(), "pre-condition"); 5590 5591 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5592 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL); 5593 5594 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5595 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL); 5596 5597 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5598 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl; 5599 5600 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5601 // We also need to mark copied objects. 5602 copy_non_heap_cl = ©_mark_non_heap_cl; 5603 copy_perm_cl = ©_mark_perm_cl; 5604 } 5605 5606 // Keep alive closure. 5607 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss); 5608 5609 // Serial Complete GC closure 5610 G1STWDrainQueueClosure drain_queue(this, &pss); 5611 5612 // Setup the soft refs policy... 5613 rp->setup_policy(false); 5614 5615 ReferenceProcessorStats stats; 5616 if (!rp->processing_is_mt()) { 5617 // Serial reference processing... 5618 stats = rp->process_discovered_references(&is_alive, 5619 &keep_alive, 5620 &drain_queue, 5621 NULL, 5622 _gc_timer_stw); 5623 } else { 5624 // Parallel reference processing 5625 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5626 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5627 5628 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5629 stats = rp->process_discovered_references(&is_alive, 5630 &keep_alive, 5631 &drain_queue, 5632 &par_task_executor, 5633 _gc_timer_stw); 5634 } 5635 5636 _gc_tracer_stw->report_gc_reference_stats(stats); 5637 // We have completed copying any necessary live referent objects 5638 // (that were not copied during the actual pause) so we can 5639 // retire any active alloc buffers 5640 pss.retire_alloc_buffers(); 5641 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5642 5643 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5644 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5645 } 5646 5647 // Weak Reference processing during an evacuation pause (part 2). 5648 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5649 double ref_enq_start = os::elapsedTime(); 5650 5651 ReferenceProcessor* rp = _ref_processor_stw; 5652 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5653 5654 // Now enqueue any remaining on the discovered lists on to 5655 // the pending list. 5656 if (!rp->processing_is_mt()) { 5657 // Serial reference processing... 5658 rp->enqueue_discovered_references(); 5659 } else { 5660 // Parallel reference enqueueing 5661 5662 assert(no_of_gc_workers == workers()->active_workers(), 5663 "Need to reset active workers"); 5664 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5665 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5666 5667 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5668 rp->enqueue_discovered_references(&par_task_executor); 5669 } 5670 5671 rp->verify_no_references_recorded(); 5672 assert(!rp->discovery_enabled(), "should have been disabled"); 5673 5674 // FIXME 5675 // CM's reference processing also cleans up the string and symbol tables. 5676 // Should we do that here also? We could, but it is a serial operation 5677 // and could significantly increase the pause time. 5678 5679 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5680 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5681 } 5682 5683 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5684 _expand_heap_after_alloc_failure = true; 5685 _evacuation_failed = false; 5686 5687 // Should G1EvacuationFailureALot be in effect for this GC? 5688 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5689 5690 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5691 5692 // Disable the hot card cache. 5693 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5694 hot_card_cache->reset_hot_cache_claimed_index(); 5695 hot_card_cache->set_use_cache(false); 5696 5697 uint n_workers; 5698 if (G1CollectedHeap::use_parallel_gc_threads()) { 5699 n_workers = 5700 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5701 workers()->active_workers(), 5702 Threads::number_of_non_daemon_threads()); 5703 assert(UseDynamicNumberOfGCThreads || 5704 n_workers == workers()->total_workers(), 5705 "If not dynamic should be using all the workers"); 5706 workers()->set_active_workers(n_workers); 5707 set_par_threads(n_workers); 5708 } else { 5709 assert(n_par_threads() == 0, 5710 "Should be the original non-parallel value"); 5711 n_workers = 1; 5712 } 5713 5714 G1ParTask g1_par_task(this, _task_queues); 5715 5716 init_for_evac_failure(NULL); 5717 5718 rem_set()->prepare_for_younger_refs_iterate(true); 5719 5720 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5721 double start_par_time_sec = os::elapsedTime(); 5722 double end_par_time_sec; 5723 5724 { 5725 StrongRootsScope srs(this); 5726 5727 if (G1CollectedHeap::use_parallel_gc_threads()) { 5728 // The individual threads will set their evac-failure closures. 5729 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5730 // These tasks use ShareHeap::_process_strong_tasks 5731 assert(UseDynamicNumberOfGCThreads || 5732 workers()->active_workers() == workers()->total_workers(), 5733 "If not dynamic should be using all the workers"); 5734 workers()->run_task(&g1_par_task); 5735 } else { 5736 g1_par_task.set_for_termination(n_workers); 5737 g1_par_task.work(0); 5738 } 5739 end_par_time_sec = os::elapsedTime(); 5740 5741 // Closing the inner scope will execute the destructor 5742 // for the StrongRootsScope object. We record the current 5743 // elapsed time before closing the scope so that time 5744 // taken for the SRS destructor is NOT included in the 5745 // reported parallel time. 5746 } 5747 5748 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5749 g1_policy()->phase_times()->record_par_time(par_time_ms); 5750 5751 double code_root_fixup_time_ms = 5752 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5753 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5754 5755 set_par_threads(0); 5756 5757 // Process any discovered reference objects - we have 5758 // to do this _before_ we retire the GC alloc regions 5759 // as we may have to copy some 'reachable' referent 5760 // objects (and their reachable sub-graphs) that were 5761 // not copied during the pause. 5762 process_discovered_references(n_workers); 5763 5764 // Weak root processing. 5765 // Note: when JSR 292 is enabled and code blobs can contain 5766 // non-perm oops then we will need to process the code blobs 5767 // here too. 5768 { 5769 G1STWIsAliveClosure is_alive(this); 5770 G1KeepAliveClosure keep_alive(this); 5771 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5772 } 5773 5774 release_gc_alloc_regions(n_workers, evacuation_info); 5775 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5776 5777 // Reset and re-enable the hot card cache. 5778 // Note the counts for the cards in the regions in the 5779 // collection set are reset when the collection set is freed. 5780 hot_card_cache->reset_hot_cache(); 5781 hot_card_cache->set_use_cache(true); 5782 5783 finalize_for_evac_failure(); 5784 5785 if (evacuation_failed()) { 5786 remove_self_forwarding_pointers(); 5787 5788 // Reset the G1EvacuationFailureALot counters and flags 5789 // Note: the values are reset only when an actual 5790 // evacuation failure occurs. 5791 NOT_PRODUCT(reset_evacuation_should_fail();) 5792 } 5793 5794 // Enqueue any remaining references remaining on the STW 5795 // reference processor's discovered lists. We need to do 5796 // this after the card table is cleaned (and verified) as 5797 // the act of enqueueing entries on to the pending list 5798 // will log these updates (and dirty their associated 5799 // cards). We need these updates logged to update any 5800 // RSets. 5801 enqueue_discovered_references(n_workers); 5802 5803 if (G1DeferredRSUpdate) { 5804 RedirtyLoggedCardTableEntryFastClosure redirty; 5805 dirty_card_queue_set().set_closure(&redirty); 5806 dirty_card_queue_set().apply_closure_to_all_completed_buffers(); 5807 5808 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5809 dcq.merge_bufferlists(&dirty_card_queue_set()); 5810 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5811 } 5812 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5813 } 5814 5815 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr, 5816 size_t* pre_used, 5817 FreeRegionList* free_list, 5818 OldRegionSet* old_proxy_set, 5819 HumongousRegionSet* humongous_proxy_set, 5820 HRRSCleanupTask* hrrs_cleanup_task, 5821 bool par) { 5822 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) { 5823 if (hr->isHumongous()) { 5824 assert(hr->startsHumongous(), "we should only see starts humongous"); 5825 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par); 5826 } else { 5827 _old_set.remove_with_proxy(hr, old_proxy_set); 5828 free_region(hr, pre_used, free_list, par); 5829 } 5830 } else { 5831 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task); 5832 } 5833 } 5834 5835 void G1CollectedHeap::free_region(HeapRegion* hr, 5836 size_t* pre_used, 5837 FreeRegionList* free_list, 5838 bool par) { 5839 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5840 assert(!hr->is_empty(), "the region should not be empty"); 5841 assert(free_list != NULL, "pre-condition"); 5842 5843 // Clear the card counts for this region. 5844 // Note: we only need to do this if the region is not young 5845 // (since we don't refine cards in young regions). 5846 if (!hr->is_young()) { 5847 _cg1r->hot_card_cache()->reset_card_counts(hr); 5848 } 5849 *pre_used += hr->used(); 5850 hr->hr_clear(par, true /* clear_space */); 5851 free_list->add_as_head(hr); 5852 } 5853 5854 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5855 size_t* pre_used, 5856 FreeRegionList* free_list, 5857 HumongousRegionSet* humongous_proxy_set, 5858 bool par) { 5859 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5860 assert(free_list != NULL, "pre-condition"); 5861 assert(humongous_proxy_set != NULL, "pre-condition"); 5862 5863 size_t hr_used = hr->used(); 5864 size_t hr_capacity = hr->capacity(); 5865 size_t hr_pre_used = 0; 5866 _humongous_set.remove_with_proxy(hr, humongous_proxy_set); 5867 // We need to read this before we make the region non-humongous, 5868 // otherwise the information will be gone. 5869 uint last_index = hr->last_hc_index(); 5870 hr->set_notHumongous(); 5871 free_region(hr, &hr_pre_used, free_list, par); 5872 5873 uint i = hr->hrs_index() + 1; 5874 while (i < last_index) { 5875 HeapRegion* curr_hr = region_at(i); 5876 assert(curr_hr->continuesHumongous(), "invariant"); 5877 curr_hr->set_notHumongous(); 5878 free_region(curr_hr, &hr_pre_used, free_list, par); 5879 i += 1; 5880 } 5881 assert(hr_pre_used == hr_used, 5882 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" " 5883 "should be the same", hr_pre_used, hr_used)); 5884 *pre_used += hr_pre_used; 5885 } 5886 5887 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used, 5888 FreeRegionList* free_list, 5889 OldRegionSet* old_proxy_set, 5890 HumongousRegionSet* humongous_proxy_set, 5891 bool par) { 5892 if (pre_used > 0) { 5893 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL; 5894 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); 5895 assert(_summary_bytes_used >= pre_used, 5896 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" " 5897 "should be >= pre_used: "SIZE_FORMAT, 5898 _summary_bytes_used, pre_used)); 5899 _summary_bytes_used -= pre_used; 5900 } 5901 if (free_list != NULL && !free_list->is_empty()) { 5902 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5903 _free_list.add_as_head(free_list); 5904 } 5905 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) { 5906 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5907 _old_set.update_from_proxy(old_proxy_set); 5908 } 5909 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) { 5910 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5911 _humongous_set.update_from_proxy(humongous_proxy_set); 5912 } 5913 } 5914 5915 class G1ParCleanupCTTask : public AbstractGangTask { 5916 CardTableModRefBS* _ct_bs; 5917 G1CollectedHeap* _g1h; 5918 HeapRegion* volatile _su_head; 5919 public: 5920 G1ParCleanupCTTask(CardTableModRefBS* ct_bs, 5921 G1CollectedHeap* g1h) : 5922 AbstractGangTask("G1 Par Cleanup CT Task"), 5923 _ct_bs(ct_bs), _g1h(g1h) { } 5924 5925 void work(uint worker_id) { 5926 HeapRegion* r; 5927 while (r = _g1h->pop_dirty_cards_region()) { 5928 clear_cards(r); 5929 } 5930 } 5931 5932 void clear_cards(HeapRegion* r) { 5933 // Cards of the survivors should have already been dirtied. 5934 if (!r->is_survivor()) { 5935 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5936 } 5937 } 5938 }; 5939 5940 #ifndef PRODUCT 5941 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5942 G1CollectedHeap* _g1h; 5943 CardTableModRefBS* _ct_bs; 5944 public: 5945 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs) 5946 : _g1h(g1h), _ct_bs(ct_bs) { } 5947 virtual bool doHeapRegion(HeapRegion* r) { 5948 if (r->is_survivor()) { 5949 _g1h->verify_dirty_region(r); 5950 } else { 5951 _g1h->verify_not_dirty_region(r); 5952 } 5953 return false; 5954 } 5955 }; 5956 5957 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5958 // All of the region should be clean. 5959 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); 5960 MemRegion mr(hr->bottom(), hr->end()); 5961 ct_bs->verify_not_dirty_region(mr); 5962 } 5963 5964 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5965 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5966 // dirty allocated blocks as they allocate them. The thread that 5967 // retires each region and replaces it with a new one will do a 5968 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5969 // not dirty that area (one less thing to have to do while holding 5970 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5971 // is dirty. 5972 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set(); 5973 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5974 ct_bs->verify_dirty_region(mr); 5975 } 5976 5977 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5978 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set(); 5979 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5980 verify_dirty_region(hr); 5981 } 5982 } 5983 5984 void G1CollectedHeap::verify_dirty_young_regions() { 5985 verify_dirty_young_list(_young_list->first_region()); 5986 } 5987 #endif 5988 5989 void G1CollectedHeap::cleanUpCardTable() { 5990 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set()); 5991 double start = os::elapsedTime(); 5992 5993 { 5994 // Iterate over the dirty cards region list. 5995 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5996 5997 if (G1CollectedHeap::use_parallel_gc_threads()) { 5998 set_par_threads(); 5999 workers()->run_task(&cleanup_task); 6000 set_par_threads(0); 6001 } else { 6002 while (_dirty_cards_region_list) { 6003 HeapRegion* r = _dirty_cards_region_list; 6004 cleanup_task.clear_cards(r); 6005 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6006 if (_dirty_cards_region_list == r) { 6007 // The last region. 6008 _dirty_cards_region_list = NULL; 6009 } 6010 r->set_next_dirty_cards_region(NULL); 6011 } 6012 } 6013 #ifndef PRODUCT 6014 if (G1VerifyCTCleanup || VerifyAfterGC) { 6015 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6016 heap_region_iterate(&cleanup_verifier); 6017 } 6018 #endif 6019 } 6020 6021 double elapsed = os::elapsedTime() - start; 6022 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6023 } 6024 6025 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6026 size_t pre_used = 0; 6027 FreeRegionList local_free_list("Local List for CSet Freeing"); 6028 6029 double young_time_ms = 0.0; 6030 double non_young_time_ms = 0.0; 6031 6032 // Since the collection set is a superset of the the young list, 6033 // all we need to do to clear the young list is clear its 6034 // head and length, and unlink any young regions in the code below 6035 _young_list->clear(); 6036 6037 G1CollectorPolicy* policy = g1_policy(); 6038 6039 double start_sec = os::elapsedTime(); 6040 bool non_young = true; 6041 6042 HeapRegion* cur = cs_head; 6043 int age_bound = -1; 6044 size_t rs_lengths = 0; 6045 6046 while (cur != NULL) { 6047 assert(!is_on_master_free_list(cur), "sanity"); 6048 if (non_young) { 6049 if (cur->is_young()) { 6050 double end_sec = os::elapsedTime(); 6051 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6052 non_young_time_ms += elapsed_ms; 6053 6054 start_sec = os::elapsedTime(); 6055 non_young = false; 6056 } 6057 } else { 6058 if (!cur->is_young()) { 6059 double end_sec = os::elapsedTime(); 6060 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6061 young_time_ms += elapsed_ms; 6062 6063 start_sec = os::elapsedTime(); 6064 non_young = true; 6065 } 6066 } 6067 6068 rs_lengths += cur->rem_set()->occupied(); 6069 6070 HeapRegion* next = cur->next_in_collection_set(); 6071 assert(cur->in_collection_set(), "bad CS"); 6072 cur->set_next_in_collection_set(NULL); 6073 cur->set_in_collection_set(false); 6074 6075 if (cur->is_young()) { 6076 int index = cur->young_index_in_cset(); 6077 assert(index != -1, "invariant"); 6078 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6079 size_t words_survived = _surviving_young_words[index]; 6080 cur->record_surv_words_in_group(words_survived); 6081 6082 // At this point the we have 'popped' cur from the collection set 6083 // (linked via next_in_collection_set()) but it is still in the 6084 // young list (linked via next_young_region()). Clear the 6085 // _next_young_region field. 6086 cur->set_next_young_region(NULL); 6087 } else { 6088 int index = cur->young_index_in_cset(); 6089 assert(index == -1, "invariant"); 6090 } 6091 6092 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6093 (!cur->is_young() && cur->young_index_in_cset() == -1), 6094 "invariant" ); 6095 6096 if (!cur->evacuation_failed()) { 6097 MemRegion used_mr = cur->used_region(); 6098 6099 // And the region is empty. 6100 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6101 free_region(cur, &pre_used, &local_free_list, false /* par */); 6102 } else { 6103 cur->uninstall_surv_rate_group(); 6104 if (cur->is_young()) { 6105 cur->set_young_index_in_cset(-1); 6106 } 6107 cur->set_not_young(); 6108 cur->set_evacuation_failed(false); 6109 // The region is now considered to be old. 6110 _old_set.add(cur); 6111 evacuation_info.increment_collectionset_used_after(cur->used()); 6112 } 6113 cur = next; 6114 } 6115 6116 evacuation_info.set_regions_freed(local_free_list.length()); 6117 policy->record_max_rs_lengths(rs_lengths); 6118 policy->cset_regions_freed(); 6119 6120 double end_sec = os::elapsedTime(); 6121 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6122 6123 if (non_young) { 6124 non_young_time_ms += elapsed_ms; 6125 } else { 6126 young_time_ms += elapsed_ms; 6127 } 6128 6129 update_sets_after_freeing_regions(pre_used, &local_free_list, 6130 NULL /* old_proxy_set */, 6131 NULL /* humongous_proxy_set */, 6132 false /* par */); 6133 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6134 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6135 } 6136 6137 // This routine is similar to the above but does not record 6138 // any policy statistics or update free lists; we are abandoning 6139 // the current incremental collection set in preparation of a 6140 // full collection. After the full GC we will start to build up 6141 // the incremental collection set again. 6142 // This is only called when we're doing a full collection 6143 // and is immediately followed by the tearing down of the young list. 6144 6145 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6146 HeapRegion* cur = cs_head; 6147 6148 while (cur != NULL) { 6149 HeapRegion* next = cur->next_in_collection_set(); 6150 assert(cur->in_collection_set(), "bad CS"); 6151 cur->set_next_in_collection_set(NULL); 6152 cur->set_in_collection_set(false); 6153 cur->set_young_index_in_cset(-1); 6154 cur = next; 6155 } 6156 } 6157 6158 void G1CollectedHeap::set_free_regions_coming() { 6159 if (G1ConcRegionFreeingVerbose) { 6160 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6161 "setting free regions coming"); 6162 } 6163 6164 assert(!free_regions_coming(), "pre-condition"); 6165 _free_regions_coming = true; 6166 } 6167 6168 void G1CollectedHeap::reset_free_regions_coming() { 6169 assert(free_regions_coming(), "pre-condition"); 6170 6171 { 6172 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6173 _free_regions_coming = false; 6174 SecondaryFreeList_lock->notify_all(); 6175 } 6176 6177 if (G1ConcRegionFreeingVerbose) { 6178 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6179 "reset free regions coming"); 6180 } 6181 } 6182 6183 void G1CollectedHeap::wait_while_free_regions_coming() { 6184 // Most of the time we won't have to wait, so let's do a quick test 6185 // first before we take the lock. 6186 if (!free_regions_coming()) { 6187 return; 6188 } 6189 6190 if (G1ConcRegionFreeingVerbose) { 6191 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6192 "waiting for free regions"); 6193 } 6194 6195 { 6196 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6197 while (free_regions_coming()) { 6198 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6199 } 6200 } 6201 6202 if (G1ConcRegionFreeingVerbose) { 6203 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6204 "done waiting for free regions"); 6205 } 6206 } 6207 6208 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6209 assert(heap_lock_held_for_gc(), 6210 "the heap lock should already be held by or for this thread"); 6211 _young_list->push_region(hr); 6212 } 6213 6214 class NoYoungRegionsClosure: public HeapRegionClosure { 6215 private: 6216 bool _success; 6217 public: 6218 NoYoungRegionsClosure() : _success(true) { } 6219 bool doHeapRegion(HeapRegion* r) { 6220 if (r->is_young()) { 6221 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6222 r->bottom(), r->end()); 6223 _success = false; 6224 } 6225 return false; 6226 } 6227 bool success() { return _success; } 6228 }; 6229 6230 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6231 bool ret = _young_list->check_list_empty(check_sample); 6232 6233 if (check_heap) { 6234 NoYoungRegionsClosure closure; 6235 heap_region_iterate(&closure); 6236 ret = ret && closure.success(); 6237 } 6238 6239 return ret; 6240 } 6241 6242 class TearDownRegionSetsClosure : public HeapRegionClosure { 6243 private: 6244 OldRegionSet *_old_set; 6245 6246 public: 6247 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { } 6248 6249 bool doHeapRegion(HeapRegion* r) { 6250 if (r->is_empty()) { 6251 // We ignore empty regions, we'll empty the free list afterwards 6252 } else if (r->is_young()) { 6253 // We ignore young regions, we'll empty the young list afterwards 6254 } else if (r->isHumongous()) { 6255 // We ignore humongous regions, we're not tearing down the 6256 // humongous region set 6257 } else { 6258 // The rest should be old 6259 _old_set->remove(r); 6260 } 6261 return false; 6262 } 6263 6264 ~TearDownRegionSetsClosure() { 6265 assert(_old_set->is_empty(), "post-condition"); 6266 } 6267 }; 6268 6269 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6270 assert_at_safepoint(true /* should_be_vm_thread */); 6271 6272 if (!free_list_only) { 6273 TearDownRegionSetsClosure cl(&_old_set); 6274 heap_region_iterate(&cl); 6275 6276 // Need to do this after the heap iteration to be able to 6277 // recognize the young regions and ignore them during the iteration. 6278 _young_list->empty_list(); 6279 } 6280 _free_list.remove_all(); 6281 } 6282 6283 class RebuildRegionSetsClosure : public HeapRegionClosure { 6284 private: 6285 bool _free_list_only; 6286 OldRegionSet* _old_set; 6287 FreeRegionList* _free_list; 6288 size_t _total_used; 6289 6290 public: 6291 RebuildRegionSetsClosure(bool free_list_only, 6292 OldRegionSet* old_set, FreeRegionList* free_list) : 6293 _free_list_only(free_list_only), 6294 _old_set(old_set), _free_list(free_list), _total_used(0) { 6295 assert(_free_list->is_empty(), "pre-condition"); 6296 if (!free_list_only) { 6297 assert(_old_set->is_empty(), "pre-condition"); 6298 } 6299 } 6300 6301 bool doHeapRegion(HeapRegion* r) { 6302 if (r->continuesHumongous()) { 6303 return false; 6304 } 6305 6306 if (r->is_empty()) { 6307 // Add free regions to the free list 6308 _free_list->add_as_tail(r); 6309 } else if (!_free_list_only) { 6310 assert(!r->is_young(), "we should not come across young regions"); 6311 6312 if (r->isHumongous()) { 6313 // We ignore humongous regions, we left the humongous set unchanged 6314 } else { 6315 // The rest should be old, add them to the old set 6316 _old_set->add(r); 6317 } 6318 _total_used += r->used(); 6319 } 6320 6321 return false; 6322 } 6323 6324 size_t total_used() { 6325 return _total_used; 6326 } 6327 }; 6328 6329 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6330 assert_at_safepoint(true /* should_be_vm_thread */); 6331 6332 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6333 heap_region_iterate(&cl); 6334 6335 if (!free_list_only) { 6336 _summary_bytes_used = cl.total_used(); 6337 } 6338 assert(_summary_bytes_used == recalculate_used(), 6339 err_msg("inconsistent _summary_bytes_used, " 6340 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6341 _summary_bytes_used, recalculate_used())); 6342 } 6343 6344 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6345 _refine_cte_cl->set_concurrent(concurrent); 6346 } 6347 6348 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6349 HeapRegion* hr = heap_region_containing(p); 6350 if (hr == NULL) { 6351 return is_in_permanent(p); 6352 } else { 6353 return hr->is_in(p); 6354 } 6355 } 6356 6357 // Methods for the mutator alloc region 6358 6359 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6360 bool force) { 6361 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6362 assert(!force || g1_policy()->can_expand_young_list(), 6363 "if force is true we should be able to expand the young list"); 6364 bool young_list_full = g1_policy()->is_young_list_full(); 6365 if (force || !young_list_full) { 6366 HeapRegion* new_alloc_region = new_region(word_size, 6367 false /* do_expand */); 6368 if (new_alloc_region != NULL) { 6369 set_region_short_lived_locked(new_alloc_region); 6370 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6371 return new_alloc_region; 6372 } 6373 } 6374 return NULL; 6375 } 6376 6377 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6378 size_t allocated_bytes) { 6379 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6380 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6381 6382 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6383 _summary_bytes_used += allocated_bytes; 6384 _hr_printer.retire(alloc_region); 6385 // We update the eden sizes here, when the region is retired, 6386 // instead of when it's allocated, since this is the point that its 6387 // used space has been recored in _summary_bytes_used. 6388 g1mm()->update_eden_size(); 6389 } 6390 6391 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6392 bool force) { 6393 return _g1h->new_mutator_alloc_region(word_size, force); 6394 } 6395 6396 void G1CollectedHeap::set_par_threads() { 6397 // Don't change the number of workers. Use the value previously set 6398 // in the workgroup. 6399 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6400 uint n_workers = workers()->active_workers(); 6401 assert(UseDynamicNumberOfGCThreads || 6402 n_workers == workers()->total_workers(), 6403 "Otherwise should be using the total number of workers"); 6404 if (n_workers == 0) { 6405 assert(false, "Should have been set in prior evacuation pause."); 6406 n_workers = ParallelGCThreads; 6407 workers()->set_active_workers(n_workers); 6408 } 6409 set_par_threads(n_workers); 6410 } 6411 6412 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6413 size_t allocated_bytes) { 6414 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6415 } 6416 6417 // Methods for the GC alloc regions 6418 6419 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6420 uint count, 6421 GCAllocPurpose ap) { 6422 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6423 6424 if (count < g1_policy()->max_regions(ap)) { 6425 HeapRegion* new_alloc_region = new_region(word_size, 6426 true /* do_expand */); 6427 if (new_alloc_region != NULL) { 6428 // We really only need to do this for old regions given that we 6429 // should never scan survivors. But it doesn't hurt to do it 6430 // for survivors too. 6431 new_alloc_region->set_saved_mark(); 6432 if (ap == GCAllocForSurvived) { 6433 new_alloc_region->set_survivor(); 6434 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6435 } else { 6436 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6437 } 6438 bool during_im = g1_policy()->during_initial_mark_pause(); 6439 new_alloc_region->note_start_of_copying(during_im); 6440 return new_alloc_region; 6441 } else { 6442 g1_policy()->note_alloc_region_limit_reached(ap); 6443 } 6444 } 6445 return NULL; 6446 } 6447 6448 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6449 size_t allocated_bytes, 6450 GCAllocPurpose ap) { 6451 bool during_im = g1_policy()->during_initial_mark_pause(); 6452 alloc_region->note_end_of_copying(during_im); 6453 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6454 if (ap == GCAllocForSurvived) { 6455 young_list()->add_survivor_region(alloc_region); 6456 } else { 6457 _old_set.add(alloc_region); 6458 } 6459 _hr_printer.retire(alloc_region); 6460 } 6461 6462 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6463 bool force) { 6464 assert(!force, "not supported for GC alloc regions"); 6465 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6466 } 6467 6468 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6469 size_t allocated_bytes) { 6470 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6471 GCAllocForSurvived); 6472 } 6473 6474 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6475 bool force) { 6476 assert(!force, "not supported for GC alloc regions"); 6477 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6478 } 6479 6480 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6481 size_t allocated_bytes) { 6482 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6483 GCAllocForTenured); 6484 } 6485 // Heap region set verification 6486 6487 class VerifyRegionListsClosure : public HeapRegionClosure { 6488 private: 6489 FreeRegionList* _free_list; 6490 OldRegionSet* _old_set; 6491 HumongousRegionSet* _humongous_set; 6492 uint _region_count; 6493 6494 public: 6495 VerifyRegionListsClosure(OldRegionSet* old_set, 6496 HumongousRegionSet* humongous_set, 6497 FreeRegionList* free_list) : 6498 _old_set(old_set), _humongous_set(humongous_set), 6499 _free_list(free_list), _region_count(0) { } 6500 6501 uint region_count() { return _region_count; } 6502 6503 bool doHeapRegion(HeapRegion* hr) { 6504 _region_count += 1; 6505 6506 if (hr->continuesHumongous()) { 6507 return false; 6508 } 6509 6510 if (hr->is_young()) { 6511 // TODO 6512 } else if (hr->startsHumongous()) { 6513 _humongous_set->verify_next_region(hr); 6514 } else if (hr->is_empty()) { 6515 _free_list->verify_next_region(hr); 6516 } else { 6517 _old_set->verify_next_region(hr); 6518 } 6519 return false; 6520 } 6521 }; 6522 6523 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6524 HeapWord* bottom) { 6525 HeapWord* end = bottom + HeapRegion::GrainWords; 6526 MemRegion mr(bottom, end); 6527 assert(_g1_reserved.contains(mr), "invariant"); 6528 // This might return NULL if the allocation fails 6529 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */); 6530 } 6531 6532 void G1CollectedHeap::verify_region_sets() { 6533 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6534 6535 // First, check the explicit lists. 6536 _free_list.verify(); 6537 { 6538 // Given that a concurrent operation might be adding regions to 6539 // the secondary free list we have to take the lock before 6540 // verifying it. 6541 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6542 _secondary_free_list.verify(); 6543 } 6544 _old_set.verify(); 6545 _humongous_set.verify(); 6546 6547 // If a concurrent region freeing operation is in progress it will 6548 // be difficult to correctly attributed any free regions we come 6549 // across to the correct free list given that they might belong to 6550 // one of several (free_list, secondary_free_list, any local lists, 6551 // etc.). So, if that's the case we will skip the rest of the 6552 // verification operation. Alternatively, waiting for the concurrent 6553 // operation to complete will have a non-trivial effect on the GC's 6554 // operation (no concurrent operation will last longer than the 6555 // interval between two calls to verification) and it might hide 6556 // any issues that we would like to catch during testing. 6557 if (free_regions_coming()) { 6558 return; 6559 } 6560 6561 // Make sure we append the secondary_free_list on the free_list so 6562 // that all free regions we will come across can be safely 6563 // attributed to the free_list. 6564 append_secondary_free_list_if_not_empty_with_lock(); 6565 6566 // Finally, make sure that the region accounting in the lists is 6567 // consistent with what we see in the heap. 6568 _old_set.verify_start(); 6569 _humongous_set.verify_start(); 6570 _free_list.verify_start(); 6571 6572 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6573 heap_region_iterate(&cl); 6574 6575 _old_set.verify_end(); 6576 _humongous_set.verify_end(); 6577 _free_list.verify_end(); 6578 }