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/codeCache.hpp" 27 #include "code/icBuffer.hpp" 28 #include "gc_implementation/g1/bufferingOopClosure.hpp" 29 #include "gc_implementation/g1/concurrentG1Refine.hpp" 30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 34 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 35 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 36 #include "gc_implementation/g1/g1EvacFailure.hpp" 37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 38 #include "gc_implementation/g1/g1Log.hpp" 39 #include "gc_implementation/g1/g1MarkSweep.hpp" 40 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 41 #include "gc_implementation/g1/g1RemSet.inline.hpp" 42 #include "gc_implementation/g1/g1YCTypes.hpp" 43 #include "gc_implementation/g1/heapRegion.inline.hpp" 44 #include "gc_implementation/g1/heapRegionRemSet.hpp" 45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 46 #include "gc_implementation/g1/vm_operations_g1.hpp" 47 #include "gc_implementation/shared/gcHeapSummary.hpp" 48 #include "gc_implementation/shared/gcTimer.hpp" 49 #include "gc_implementation/shared/gcTrace.hpp" 50 #include "gc_implementation/shared/gcTraceTime.hpp" 51 #include "gc_implementation/shared/isGCActiveMark.hpp" 52 #include "memory/gcLocker.inline.hpp" 53 #include "memory/generationSpec.hpp" 54 #include "memory/iterator.hpp" 55 #include "memory/referenceProcessor.hpp" 56 #include "oops/oop.inline.hpp" 57 #include "oops/oop.pcgc.inline.hpp" 58 #include "runtime/vmThread.hpp" 59 #include "utilities/ticks.hpp" 60 61 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 62 63 // turn it on so that the contents of the young list (scan-only / 64 // to-be-collected) are printed at "strategic" points before / during 65 // / after the collection --- this is useful for debugging 66 #define YOUNG_LIST_VERBOSE 0 67 // CURRENT STATUS 68 // This file is under construction. Search for "FIXME". 69 70 // INVARIANTS/NOTES 71 // 72 // All allocation activity covered by the G1CollectedHeap interface is 73 // serialized by acquiring the HeapLock. This happens in mem_allocate 74 // and allocate_new_tlab, which are the "entry" points to the 75 // allocation code from the rest of the JVM. (Note that this does not 76 // apply to TLAB allocation, which is not part of this interface: it 77 // is done by clients of this interface.) 78 79 // Notes on implementation of parallelism in different tasks. 80 // 81 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 82 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 83 // It does use run_task() which sets _n_workers in the task. 84 // G1ParTask executes g1_process_strong_roots() -> 85 // SharedHeap::process_strong_roots() which calls eventually to 86 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 87 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 88 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 89 // 90 91 // Local to this file. 92 93 class RefineCardTableEntryClosure: public CardTableEntryClosure { 94 SuspendibleThreadSet* _sts; 95 G1RemSet* _g1rs; 96 ConcurrentG1Refine* _cg1r; 97 bool _concurrent; 98 public: 99 RefineCardTableEntryClosure(SuspendibleThreadSet* sts, 100 G1RemSet* g1rs, 101 ConcurrentG1Refine* cg1r) : 102 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true) 103 {} 104 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 105 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false); 106 // This path is executed by the concurrent refine or mutator threads, 107 // concurrently, and so we do not care if card_ptr contains references 108 // that point into the collection set. 109 assert(!oops_into_cset, "should be"); 110 111 if (_concurrent && _sts->should_yield()) { 112 // Caller will actually yield. 113 return false; 114 } 115 // Otherwise, we finished successfully; return true. 116 return true; 117 } 118 void set_concurrent(bool b) { _concurrent = b; } 119 }; 120 121 122 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 123 int _calls; 124 G1CollectedHeap* _g1h; 125 CardTableModRefBS* _ctbs; 126 int _histo[256]; 127 public: 128 ClearLoggedCardTableEntryClosure() : 129 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) 130 { 131 for (int i = 0; i < 256; i++) _histo[i] = 0; 132 } 133 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 134 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 135 _calls++; 136 unsigned char* ujb = (unsigned char*)card_ptr; 137 int ind = (int)(*ujb); 138 _histo[ind]++; 139 *card_ptr = -1; 140 } 141 return true; 142 } 143 int calls() { return _calls; } 144 void print_histo() { 145 gclog_or_tty->print_cr("Card table value histogram:"); 146 for (int i = 0; i < 256; i++) { 147 if (_histo[i] != 0) { 148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 149 } 150 } 151 } 152 }; 153 154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { 155 int _calls; 156 G1CollectedHeap* _g1h; 157 CardTableModRefBS* _ctbs; 158 public: 159 RedirtyLoggedCardTableEntryClosure() : 160 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {} 161 162 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 163 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 164 _calls++; 165 *card_ptr = 0; 166 } 167 return true; 168 } 169 int calls() { return _calls; } 170 }; 171 172 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { 173 public: 174 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 175 *card_ptr = CardTableModRefBS::dirty_card_val(); 176 return true; 177 } 178 }; 179 180 YoungList::YoungList(G1CollectedHeap* g1h) : 181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 183 guarantee(check_list_empty(false), "just making sure..."); 184 } 185 186 void YoungList::push_region(HeapRegion *hr) { 187 assert(!hr->is_young(), "should not already be young"); 188 assert(hr->get_next_young_region() == NULL, "cause it should!"); 189 190 hr->set_next_young_region(_head); 191 _head = hr; 192 193 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 194 ++_length; 195 } 196 197 void YoungList::add_survivor_region(HeapRegion* hr) { 198 assert(hr->is_survivor(), "should be flagged as survivor region"); 199 assert(hr->get_next_young_region() == NULL, "cause it should!"); 200 201 hr->set_next_young_region(_survivor_head); 202 if (_survivor_head == NULL) { 203 _survivor_tail = hr; 204 } 205 _survivor_head = hr; 206 ++_survivor_length; 207 } 208 209 void YoungList::empty_list(HeapRegion* list) { 210 while (list != NULL) { 211 HeapRegion* next = list->get_next_young_region(); 212 list->set_next_young_region(NULL); 213 list->uninstall_surv_rate_group(); 214 list->set_not_young(); 215 list = next; 216 } 217 } 218 219 void YoungList::empty_list() { 220 assert(check_list_well_formed(), "young list should be well formed"); 221 222 empty_list(_head); 223 _head = NULL; 224 _length = 0; 225 226 empty_list(_survivor_head); 227 _survivor_head = NULL; 228 _survivor_tail = NULL; 229 _survivor_length = 0; 230 231 _last_sampled_rs_lengths = 0; 232 233 assert(check_list_empty(false), "just making sure..."); 234 } 235 236 bool YoungList::check_list_well_formed() { 237 bool ret = true; 238 239 uint length = 0; 240 HeapRegion* curr = _head; 241 HeapRegion* last = NULL; 242 while (curr != NULL) { 243 if (!curr->is_young()) { 244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 245 "incorrectly tagged (y: %d, surv: %d)", 246 curr->bottom(), curr->end(), 247 curr->is_young(), curr->is_survivor()); 248 ret = false; 249 } 250 ++length; 251 last = curr; 252 curr = curr->get_next_young_region(); 253 } 254 ret = ret && (length == _length); 255 256 if (!ret) { 257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 258 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 259 length, _length); 260 } 261 262 return ret; 263 } 264 265 bool YoungList::check_list_empty(bool check_sample) { 266 bool ret = true; 267 268 if (_length != 0) { 269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 270 _length); 271 ret = false; 272 } 273 if (check_sample && _last_sampled_rs_lengths != 0) { 274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 275 ret = false; 276 } 277 if (_head != NULL) { 278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 279 ret = false; 280 } 281 if (!ret) { 282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 283 } 284 285 return ret; 286 } 287 288 void 289 YoungList::rs_length_sampling_init() { 290 _sampled_rs_lengths = 0; 291 _curr = _head; 292 } 293 294 bool 295 YoungList::rs_length_sampling_more() { 296 return _curr != NULL; 297 } 298 299 void 300 YoungList::rs_length_sampling_next() { 301 assert( _curr != NULL, "invariant" ); 302 size_t rs_length = _curr->rem_set()->occupied(); 303 304 _sampled_rs_lengths += rs_length; 305 306 // The current region may not yet have been added to the 307 // incremental collection set (it gets added when it is 308 // retired as the current allocation region). 309 if (_curr->in_collection_set()) { 310 // Update the collection set policy information for this region 311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 312 } 313 314 _curr = _curr->get_next_young_region(); 315 if (_curr == NULL) { 316 _last_sampled_rs_lengths = _sampled_rs_lengths; 317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 318 } 319 } 320 321 void 322 YoungList::reset_auxilary_lists() { 323 guarantee( is_empty(), "young list should be empty" ); 324 assert(check_list_well_formed(), "young list should be well formed"); 325 326 // Add survivor regions to SurvRateGroup. 327 _g1h->g1_policy()->note_start_adding_survivor_regions(); 328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 329 330 int young_index_in_cset = 0; 331 for (HeapRegion* curr = _survivor_head; 332 curr != NULL; 333 curr = curr->get_next_young_region()) { 334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 335 336 // The region is a non-empty survivor so let's add it to 337 // the incremental collection set for the next evacuation 338 // pause. 339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 340 young_index_in_cset += 1; 341 } 342 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 343 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 344 345 _head = _survivor_head; 346 _length = _survivor_length; 347 if (_survivor_head != NULL) { 348 assert(_survivor_tail != NULL, "cause it shouldn't be"); 349 assert(_survivor_length > 0, "invariant"); 350 _survivor_tail->set_next_young_region(NULL); 351 } 352 353 // Don't clear the survivor list handles until the start of 354 // the next evacuation pause - we need it in order to re-tag 355 // the survivor regions from this evacuation pause as 'young' 356 // at the start of the next. 357 358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 359 360 assert(check_list_well_formed(), "young list should be well formed"); 361 } 362 363 void YoungList::print() { 364 HeapRegion* lists[] = {_head, _survivor_head}; 365 const char* names[] = {"YOUNG", "SURVIVOR"}; 366 367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 369 HeapRegion *curr = lists[list]; 370 if (curr == NULL) 371 gclog_or_tty->print_cr(" empty"); 372 while (curr != NULL) { 373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 374 HR_FORMAT_PARAMS(curr), 375 curr->prev_top_at_mark_start(), 376 curr->next_top_at_mark_start(), 377 curr->age_in_surv_rate_group_cond()); 378 curr = curr->get_next_young_region(); 379 } 380 } 381 382 gclog_or_tty->print_cr(""); 383 } 384 385 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 386 { 387 // Claim the right to put the region on the dirty cards region list 388 // by installing a self pointer. 389 HeapRegion* next = hr->get_next_dirty_cards_region(); 390 if (next == NULL) { 391 HeapRegion* res = (HeapRegion*) 392 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 393 NULL); 394 if (res == NULL) { 395 HeapRegion* head; 396 do { 397 // Put the region to the dirty cards region list. 398 head = _dirty_cards_region_list; 399 next = (HeapRegion*) 400 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 401 if (next == head) { 402 assert(hr->get_next_dirty_cards_region() == hr, 403 "hr->get_next_dirty_cards_region() != hr"); 404 if (next == NULL) { 405 // The last region in the list points to itself. 406 hr->set_next_dirty_cards_region(hr); 407 } else { 408 hr->set_next_dirty_cards_region(next); 409 } 410 } 411 } while (next != head); 412 } 413 } 414 } 415 416 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 417 { 418 HeapRegion* head; 419 HeapRegion* hr; 420 do { 421 head = _dirty_cards_region_list; 422 if (head == NULL) { 423 return NULL; 424 } 425 HeapRegion* new_head = head->get_next_dirty_cards_region(); 426 if (head == new_head) { 427 // The last region. 428 new_head = NULL; 429 } 430 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 431 head); 432 } while (hr != head); 433 assert(hr != NULL, "invariant"); 434 hr->set_next_dirty_cards_region(NULL); 435 return hr; 436 } 437 438 void G1CollectedHeap::stop_conc_gc_threads() { 439 _cg1r->stop(); 440 _cmThread->stop(); 441 } 442 443 #ifdef ASSERT 444 // A region is added to the collection set as it is retired 445 // so an address p can point to a region which will be in the 446 // collection set but has not yet been retired. This method 447 // therefore is only accurate during a GC pause after all 448 // regions have been retired. It is used for debugging 449 // to check if an nmethod has references to objects that can 450 // be move during a partial collection. Though it can be 451 // inaccurate, it is sufficient for G1 because the conservative 452 // implementation of is_scavengable() for G1 will indicate that 453 // all nmethods must be scanned during a partial collection. 454 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 455 HeapRegion* hr = heap_region_containing(p); 456 return hr != NULL && hr->in_collection_set(); 457 } 458 #endif 459 460 // Returns true if the reference points to an object that 461 // can move in an incremental collection. 462 bool G1CollectedHeap::is_scavengable(const void* p) { 463 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 464 G1CollectorPolicy* g1p = g1h->g1_policy(); 465 HeapRegion* hr = heap_region_containing(p); 466 if (hr == NULL) { 467 // null 468 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p)); 469 return false; 470 } else { 471 return !hr->isHumongous(); 472 } 473 } 474 475 void G1CollectedHeap::check_ct_logs_at_safepoint() { 476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 477 CardTableModRefBS* ct_bs = g1_barrier_set(); 478 479 // Count the dirty cards at the start. 480 CountNonCleanMemRegionClosure count1(this); 481 ct_bs->mod_card_iterate(&count1); 482 int orig_count = count1.n(); 483 484 // First clear the logged cards. 485 ClearLoggedCardTableEntryClosure clear; 486 dcqs.set_closure(&clear); 487 dcqs.apply_closure_to_all_completed_buffers(); 488 dcqs.iterate_closure_all_threads(false); 489 clear.print_histo(); 490 491 // Now ensure that there's no dirty cards. 492 CountNonCleanMemRegionClosure count2(this); 493 ct_bs->mod_card_iterate(&count2); 494 if (count2.n() != 0) { 495 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 496 count2.n(), orig_count); 497 } 498 guarantee(count2.n() == 0, "Card table should be clean."); 499 500 RedirtyLoggedCardTableEntryClosure redirty; 501 JavaThread::dirty_card_queue_set().set_closure(&redirty); 502 dcqs.apply_closure_to_all_completed_buffers(); 503 dcqs.iterate_closure_all_threads(false); 504 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 505 clear.calls(), orig_count); 506 guarantee(redirty.calls() == clear.calls(), 507 "Or else mechanism is broken."); 508 509 CountNonCleanMemRegionClosure count3(this); 510 ct_bs->mod_card_iterate(&count3); 511 if (count3.n() != orig_count) { 512 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 513 orig_count, count3.n()); 514 guarantee(count3.n() >= orig_count, "Should have restored them all."); 515 } 516 517 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 518 } 519 520 // Private class members. 521 522 G1CollectedHeap* G1CollectedHeap::_g1h; 523 524 // Private methods. 525 526 HeapRegion* 527 G1CollectedHeap::new_region_try_secondary_free_list() { 528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 529 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 530 if (!_secondary_free_list.is_empty()) { 531 if (G1ConcRegionFreeingVerbose) { 532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 533 "secondary_free_list has %u entries", 534 _secondary_free_list.length()); 535 } 536 // It looks as if there are free regions available on the 537 // secondary_free_list. Let's move them to the free_list and try 538 // again to allocate from it. 539 append_secondary_free_list(); 540 541 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 542 "empty we should have moved at least one entry to the free_list"); 543 HeapRegion* res = _free_list.remove_head(); 544 if (G1ConcRegionFreeingVerbose) { 545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 546 "allocated "HR_FORMAT" from secondary_free_list", 547 HR_FORMAT_PARAMS(res)); 548 } 549 return res; 550 } 551 552 // Wait here until we get notified either when (a) there are no 553 // more free regions coming or (b) some regions have been moved on 554 // the secondary_free_list. 555 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 556 } 557 558 if (G1ConcRegionFreeingVerbose) { 559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 560 "could not allocate from secondary_free_list"); 561 } 562 return NULL; 563 } 564 565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) { 566 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 567 "the only time we use this to allocate a humongous region is " 568 "when we are allocating a single humongous region"); 569 570 HeapRegion* res; 571 if (G1StressConcRegionFreeing) { 572 if (!_secondary_free_list.is_empty()) { 573 if (G1ConcRegionFreeingVerbose) { 574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 575 "forced to look at the secondary_free_list"); 576 } 577 res = new_region_try_secondary_free_list(); 578 if (res != NULL) { 579 return res; 580 } 581 } 582 } 583 res = _free_list.remove_head_or_null(); 584 if (res == NULL) { 585 if (G1ConcRegionFreeingVerbose) { 586 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 587 "res == NULL, trying the secondary_free_list"); 588 } 589 res = new_region_try_secondary_free_list(); 590 } 591 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 592 // Currently, only attempts to allocate GC alloc regions set 593 // do_expand to true. So, we should only reach here during a 594 // safepoint. If this assumption changes we might have to 595 // reconsider the use of _expand_heap_after_alloc_failure. 596 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 597 598 ergo_verbose1(ErgoHeapSizing, 599 "attempt heap expansion", 600 ergo_format_reason("region allocation request failed") 601 ergo_format_byte("allocation request"), 602 word_size * HeapWordSize); 603 if (expand(word_size * HeapWordSize)) { 604 // Given that expand() succeeded in expanding the heap, and we 605 // always expand the heap by an amount aligned to the heap 606 // region size, the free list should in theory not be empty. So 607 // it would probably be OK to use remove_head(). But the extra 608 // check for NULL is unlikely to be a performance issue here (we 609 // just expanded the heap!) so let's just be conservative and 610 // use remove_head_or_null(). 611 res = _free_list.remove_head_or_null(); 612 } else { 613 _expand_heap_after_alloc_failure = false; 614 } 615 } 616 return res; 617 } 618 619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 620 size_t word_size) { 621 assert(isHumongous(word_size), "word_size should be humongous"); 622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 623 624 uint first = G1_NULL_HRS_INDEX; 625 if (num_regions == 1) { 626 // Only one region to allocate, no need to go through the slower 627 // path. The caller will attempt the expansion if this fails, so 628 // let's not try to expand here too. 629 HeapRegion* hr = new_region(word_size, false /* do_expand */); 630 if (hr != NULL) { 631 first = hr->hrs_index(); 632 } else { 633 first = G1_NULL_HRS_INDEX; 634 } 635 } else { 636 // We can't allocate humongous regions while cleanupComplete() is 637 // running, since some of the regions we find to be empty might not 638 // yet be added to the free list and it is not straightforward to 639 // know which list they are on so that we can remove them. Note 640 // that we only need to do this if we need to allocate more than 641 // one region to satisfy the current humongous allocation 642 // request. If we are only allocating one region we use the common 643 // region allocation code (see above). 644 wait_while_free_regions_coming(); 645 append_secondary_free_list_if_not_empty_with_lock(); 646 647 if (free_regions() >= num_regions) { 648 first = _hrs.find_contiguous(num_regions); 649 if (first != G1_NULL_HRS_INDEX) { 650 for (uint i = first; i < first + num_regions; ++i) { 651 HeapRegion* hr = region_at(i); 652 assert(hr->is_empty(), "sanity"); 653 assert(is_on_master_free_list(hr), "sanity"); 654 hr->set_pending_removal(true); 655 } 656 _free_list.remove_all_pending(num_regions); 657 } 658 } 659 } 660 return first; 661 } 662 663 HeapWord* 664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 665 uint num_regions, 666 size_t word_size) { 667 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 668 assert(isHumongous(word_size), "word_size should be humongous"); 669 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 670 671 // Index of last region in the series + 1. 672 uint last = first + num_regions; 673 674 // We need to initialize the region(s) we just discovered. This is 675 // a bit tricky given that it can happen concurrently with 676 // refinement threads refining cards on these regions and 677 // potentially wanting to refine the BOT as they are scanning 678 // those cards (this can happen shortly after a cleanup; see CR 679 // 6991377). So we have to set up the region(s) carefully and in 680 // a specific order. 681 682 // The word size sum of all the regions we will allocate. 683 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 684 assert(word_size <= word_size_sum, "sanity"); 685 686 // This will be the "starts humongous" region. 687 HeapRegion* first_hr = region_at(first); 688 // The header of the new object will be placed at the bottom of 689 // the first region. 690 HeapWord* new_obj = first_hr->bottom(); 691 // This will be the new end of the first region in the series that 692 // should also match the end of the last region in the series. 693 HeapWord* new_end = new_obj + word_size_sum; 694 // This will be the new top of the first region that will reflect 695 // this allocation. 696 HeapWord* new_top = new_obj + word_size; 697 698 // First, we need to zero the header of the space that we will be 699 // allocating. When we update top further down, some refinement 700 // threads might try to scan the region. By zeroing the header we 701 // ensure that any thread that will try to scan the region will 702 // come across the zero klass word and bail out. 703 // 704 // NOTE: It would not have been correct to have used 705 // CollectedHeap::fill_with_object() and make the space look like 706 // an int array. The thread that is doing the allocation will 707 // later update the object header to a potentially different array 708 // type and, for a very short period of time, the klass and length 709 // fields will be inconsistent. This could cause a refinement 710 // thread to calculate the object size incorrectly. 711 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 712 713 // We will set up the first region as "starts humongous". This 714 // will also update the BOT covering all the regions to reflect 715 // that there is a single object that starts at the bottom of the 716 // first region. 717 first_hr->set_startsHumongous(new_top, new_end); 718 719 // Then, if there are any, we will set up the "continues 720 // humongous" regions. 721 HeapRegion* hr = NULL; 722 for (uint i = first + 1; i < last; ++i) { 723 hr = region_at(i); 724 hr->set_continuesHumongous(first_hr); 725 } 726 // If we have "continues humongous" regions (hr != NULL), then the 727 // end of the last one should match new_end. 728 assert(hr == NULL || hr->end() == new_end, "sanity"); 729 730 // Up to this point no concurrent thread would have been able to 731 // do any scanning on any region in this series. All the top 732 // fields still point to bottom, so the intersection between 733 // [bottom,top] and [card_start,card_end] will be empty. Before we 734 // update the top fields, we'll do a storestore to make sure that 735 // no thread sees the update to top before the zeroing of the 736 // object header and the BOT initialization. 737 OrderAccess::storestore(); 738 739 // Now that the BOT and the object header have been initialized, 740 // we can update top of the "starts humongous" region. 741 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 742 "new_top should be in this region"); 743 first_hr->set_top(new_top); 744 if (_hr_printer.is_active()) { 745 HeapWord* bottom = first_hr->bottom(); 746 HeapWord* end = first_hr->orig_end(); 747 if ((first + 1) == last) { 748 // the series has a single humongous region 749 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 750 } else { 751 // the series has more than one humongous regions 752 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 753 } 754 } 755 756 // Now, we will update the top fields of the "continues humongous" 757 // regions. The reason we need to do this is that, otherwise, 758 // these regions would look empty and this will confuse parts of 759 // G1. For example, the code that looks for a consecutive number 760 // of empty regions will consider them empty and try to 761 // re-allocate them. We can extend is_empty() to also include 762 // !continuesHumongous(), but it is easier to just update the top 763 // fields here. The way we set top for all regions (i.e., top == 764 // end for all regions but the last one, top == new_top for the 765 // last one) is actually used when we will free up the humongous 766 // region in free_humongous_region(). 767 hr = NULL; 768 for (uint i = first + 1; i < last; ++i) { 769 hr = region_at(i); 770 if ((i + 1) == last) { 771 // last continues humongous region 772 assert(hr->bottom() < new_top && new_top <= hr->end(), 773 "new_top should fall on this region"); 774 hr->set_top(new_top); 775 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 776 } else { 777 // not last one 778 assert(new_top > hr->end(), "new_top should be above this region"); 779 hr->set_top(hr->end()); 780 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 781 } 782 } 783 // If we have continues humongous regions (hr != NULL), then the 784 // end of the last one should match new_end and its top should 785 // match new_top. 786 assert(hr == NULL || 787 (hr->end() == new_end && hr->top() == new_top), "sanity"); 788 789 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 790 _summary_bytes_used += first_hr->used(); 791 _humongous_set.add(first_hr); 792 793 return new_obj; 794 } 795 796 // If could fit into free regions w/o expansion, try. 797 // Otherwise, if can expand, do so. 798 // Otherwise, if using ex regions might help, try with ex given back. 799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 800 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 801 802 verify_region_sets_optional(); 803 804 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 805 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 806 uint x_num = expansion_regions(); 807 uint fs = _hrs.free_suffix(); 808 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 809 if (first == G1_NULL_HRS_INDEX) { 810 // The only thing we can do now is attempt expansion. 811 if (fs + x_num >= num_regions) { 812 // If the number of regions we're trying to allocate for this 813 // object is at most the number of regions in the free suffix, 814 // then the call to humongous_obj_allocate_find_first() above 815 // should have succeeded and we wouldn't be here. 816 // 817 // We should only be trying to expand when the free suffix is 818 // not sufficient for the object _and_ we have some expansion 819 // room available. 820 assert(num_regions > fs, "earlier allocation should have succeeded"); 821 822 ergo_verbose1(ErgoHeapSizing, 823 "attempt heap expansion", 824 ergo_format_reason("humongous allocation request failed") 825 ergo_format_byte("allocation request"), 826 word_size * HeapWordSize); 827 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 828 // Even though the heap was expanded, it might not have 829 // reached the desired size. So, we cannot assume that the 830 // allocation will succeed. 831 first = humongous_obj_allocate_find_first(num_regions, word_size); 832 } 833 } 834 } 835 836 HeapWord* result = NULL; 837 if (first != G1_NULL_HRS_INDEX) { 838 result = 839 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 840 assert(result != NULL, "it should always return a valid result"); 841 842 // A successful humongous object allocation changes the used space 843 // information of the old generation so we need to recalculate the 844 // sizes and update the jstat counters here. 845 g1mm()->update_sizes(); 846 } 847 848 verify_region_sets_optional(); 849 850 return result; 851 } 852 853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 854 assert_heap_not_locked_and_not_at_safepoint(); 855 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 856 857 unsigned int dummy_gc_count_before; 858 int dummy_gclocker_retry_count = 0; 859 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 860 } 861 862 HeapWord* 863 G1CollectedHeap::mem_allocate(size_t word_size, 864 bool* gc_overhead_limit_was_exceeded) { 865 assert_heap_not_locked_and_not_at_safepoint(); 866 867 // Loop until the allocation is satisfied, or unsatisfied after GC. 868 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 869 unsigned int gc_count_before; 870 871 HeapWord* result = NULL; 872 if (!isHumongous(word_size)) { 873 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 874 } else { 875 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 876 } 877 if (result != NULL) { 878 return result; 879 } 880 881 // Create the garbage collection operation... 882 VM_G1CollectForAllocation op(gc_count_before, word_size); 883 // ...and get the VM thread to execute it. 884 VMThread::execute(&op); 885 886 if (op.prologue_succeeded() && op.pause_succeeded()) { 887 // If the operation was successful we'll return the result even 888 // if it is NULL. If the allocation attempt failed immediately 889 // after a Full GC, it's unlikely we'll be able to allocate now. 890 HeapWord* result = op.result(); 891 if (result != NULL && !isHumongous(word_size)) { 892 // Allocations that take place on VM operations do not do any 893 // card dirtying and we have to do it here. We only have to do 894 // this for non-humongous allocations, though. 895 dirty_young_block(result, word_size); 896 } 897 return result; 898 } else { 899 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 900 return NULL; 901 } 902 assert(op.result() == NULL, 903 "the result should be NULL if the VM op did not succeed"); 904 } 905 906 // Give a warning if we seem to be looping forever. 907 if ((QueuedAllocationWarningCount > 0) && 908 (try_count % QueuedAllocationWarningCount == 0)) { 909 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 910 } 911 } 912 913 ShouldNotReachHere(); 914 return NULL; 915 } 916 917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 918 unsigned int *gc_count_before_ret, 919 int* gclocker_retry_count_ret) { 920 // Make sure you read the note in attempt_allocation_humongous(). 921 922 assert_heap_not_locked_and_not_at_safepoint(); 923 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 924 "be called for humongous allocation requests"); 925 926 // We should only get here after the first-level allocation attempt 927 // (attempt_allocation()) failed to allocate. 928 929 // We will loop until a) we manage to successfully perform the 930 // allocation or b) we successfully schedule a collection which 931 // fails to perform the allocation. b) is the only case when we'll 932 // return NULL. 933 HeapWord* result = NULL; 934 for (int try_count = 1; /* we'll return */; try_count += 1) { 935 bool should_try_gc; 936 unsigned int gc_count_before; 937 938 { 939 MutexLockerEx x(Heap_lock); 940 941 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 942 false /* bot_updates */); 943 if (result != NULL) { 944 return result; 945 } 946 947 // If we reach here, attempt_allocation_locked() above failed to 948 // allocate a new region. So the mutator alloc region should be NULL. 949 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 950 951 if (GC_locker::is_active_and_needs_gc()) { 952 if (g1_policy()->can_expand_young_list()) { 953 // No need for an ergo verbose message here, 954 // can_expand_young_list() does this when it returns true. 955 result = _mutator_alloc_region.attempt_allocation_force(word_size, 956 false /* bot_updates */); 957 if (result != NULL) { 958 return result; 959 } 960 } 961 should_try_gc = false; 962 } else { 963 // The GCLocker may not be active but the GCLocker initiated 964 // GC may not yet have been performed (GCLocker::needs_gc() 965 // returns true). In this case we do not try this GC and 966 // wait until the GCLocker initiated GC is performed, and 967 // then retry the allocation. 968 if (GC_locker::needs_gc()) { 969 should_try_gc = false; 970 } else { 971 // Read the GC count while still holding the Heap_lock. 972 gc_count_before = total_collections(); 973 should_try_gc = true; 974 } 975 } 976 } 977 978 if (should_try_gc) { 979 bool succeeded; 980 result = do_collection_pause(word_size, gc_count_before, &succeeded, 981 GCCause::_g1_inc_collection_pause); 982 if (result != NULL) { 983 assert(succeeded, "only way to get back a non-NULL result"); 984 return result; 985 } 986 987 if (succeeded) { 988 // If we get here we successfully scheduled a collection which 989 // failed to allocate. No point in trying to allocate 990 // further. We'll just return NULL. 991 MutexLockerEx x(Heap_lock); 992 *gc_count_before_ret = total_collections(); 993 return NULL; 994 } 995 } else { 996 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 997 MutexLockerEx x(Heap_lock); 998 *gc_count_before_ret = total_collections(); 999 return NULL; 1000 } 1001 // The GCLocker is either active or the GCLocker initiated 1002 // GC has not yet been performed. Stall until it is and 1003 // then retry the allocation. 1004 GC_locker::stall_until_clear(); 1005 (*gclocker_retry_count_ret) += 1; 1006 } 1007 1008 // We can reach here if we were unsuccessful in scheduling a 1009 // collection (because another thread beat us to it) or if we were 1010 // stalled due to the GC locker. In either can we should retry the 1011 // allocation attempt in case another thread successfully 1012 // performed a collection and reclaimed enough space. We do the 1013 // first attempt (without holding the Heap_lock) here and the 1014 // follow-on attempt will be at the start of the next loop 1015 // iteration (after taking the Heap_lock). 1016 result = _mutator_alloc_region.attempt_allocation(word_size, 1017 false /* bot_updates */); 1018 if (result != NULL) { 1019 return result; 1020 } 1021 1022 // Give a warning if we seem to be looping forever. 1023 if ((QueuedAllocationWarningCount > 0) && 1024 (try_count % QueuedAllocationWarningCount == 0)) { 1025 warning("G1CollectedHeap::attempt_allocation_slow() " 1026 "retries %d times", try_count); 1027 } 1028 } 1029 1030 ShouldNotReachHere(); 1031 return NULL; 1032 } 1033 1034 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1035 unsigned int * gc_count_before_ret, 1036 int* gclocker_retry_count_ret) { 1037 // The structure of this method has a lot of similarities to 1038 // attempt_allocation_slow(). The reason these two were not merged 1039 // into a single one is that such a method would require several "if 1040 // allocation is not humongous do this, otherwise do that" 1041 // conditional paths which would obscure its flow. In fact, an early 1042 // version of this code did use a unified method which was harder to 1043 // follow and, as a result, it had subtle bugs that were hard to 1044 // track down. So keeping these two methods separate allows each to 1045 // be more readable. It will be good to keep these two in sync as 1046 // much as possible. 1047 1048 assert_heap_not_locked_and_not_at_safepoint(); 1049 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1050 "should only be called for humongous allocations"); 1051 1052 // Humongous objects can exhaust the heap quickly, so we should check if we 1053 // need to start a marking cycle at each humongous object allocation. We do 1054 // the check before we do the actual allocation. The reason for doing it 1055 // before the allocation is that we avoid having to keep track of the newly 1056 // allocated memory while we do a GC. 1057 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1058 word_size)) { 1059 collect(GCCause::_g1_humongous_allocation); 1060 } 1061 1062 // We will loop until a) we manage to successfully perform the 1063 // allocation or b) we successfully schedule a collection which 1064 // fails to perform the allocation. b) is the only case when we'll 1065 // return NULL. 1066 HeapWord* result = NULL; 1067 for (int try_count = 1; /* we'll return */; try_count += 1) { 1068 bool should_try_gc; 1069 unsigned int gc_count_before; 1070 1071 { 1072 MutexLockerEx x(Heap_lock); 1073 1074 // Given that humongous objects are not allocated in young 1075 // regions, we'll first try to do the allocation without doing a 1076 // collection hoping that there's enough space in the heap. 1077 result = humongous_obj_allocate(word_size); 1078 if (result != NULL) { 1079 return result; 1080 } 1081 1082 if (GC_locker::is_active_and_needs_gc()) { 1083 should_try_gc = false; 1084 } else { 1085 // The GCLocker may not be active but the GCLocker initiated 1086 // GC may not yet have been performed (GCLocker::needs_gc() 1087 // returns true). In this case we do not try this GC and 1088 // wait until the GCLocker initiated GC is performed, and 1089 // then retry the allocation. 1090 if (GC_locker::needs_gc()) { 1091 should_try_gc = false; 1092 } else { 1093 // Read the GC count while still holding the Heap_lock. 1094 gc_count_before = total_collections(); 1095 should_try_gc = true; 1096 } 1097 } 1098 } 1099 1100 if (should_try_gc) { 1101 // If we failed to allocate the humongous object, we should try to 1102 // do a collection pause (if we're allowed) in case it reclaims 1103 // enough space for the allocation to succeed after the pause. 1104 1105 bool succeeded; 1106 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1107 GCCause::_g1_humongous_allocation); 1108 if (result != NULL) { 1109 assert(succeeded, "only way to get back a non-NULL result"); 1110 return result; 1111 } 1112 1113 if (succeeded) { 1114 // If we get here we successfully scheduled a collection which 1115 // failed to allocate. No point in trying to allocate 1116 // further. We'll just return NULL. 1117 MutexLockerEx x(Heap_lock); 1118 *gc_count_before_ret = total_collections(); 1119 return NULL; 1120 } 1121 } else { 1122 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1123 MutexLockerEx x(Heap_lock); 1124 *gc_count_before_ret = total_collections(); 1125 return NULL; 1126 } 1127 // The GCLocker is either active or the GCLocker initiated 1128 // GC has not yet been performed. Stall until it is and 1129 // then retry the allocation. 1130 GC_locker::stall_until_clear(); 1131 (*gclocker_retry_count_ret) += 1; 1132 } 1133 1134 // We can reach here if we were unsuccessful in scheduling a 1135 // collection (because another thread beat us to it) or if we were 1136 // stalled due to the GC locker. In either can we should retry the 1137 // allocation attempt in case another thread successfully 1138 // performed a collection and reclaimed enough space. Give a 1139 // warning if we seem to be looping forever. 1140 1141 if ((QueuedAllocationWarningCount > 0) && 1142 (try_count % QueuedAllocationWarningCount == 0)) { 1143 warning("G1CollectedHeap::attempt_allocation_humongous() " 1144 "retries %d times", try_count); 1145 } 1146 } 1147 1148 ShouldNotReachHere(); 1149 return NULL; 1150 } 1151 1152 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1153 bool expect_null_mutator_alloc_region) { 1154 assert_at_safepoint(true /* should_be_vm_thread */); 1155 assert(_mutator_alloc_region.get() == NULL || 1156 !expect_null_mutator_alloc_region, 1157 "the current alloc region was unexpectedly found to be non-NULL"); 1158 1159 if (!isHumongous(word_size)) { 1160 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1161 false /* bot_updates */); 1162 } else { 1163 HeapWord* result = humongous_obj_allocate(word_size); 1164 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1165 g1_policy()->set_initiate_conc_mark_if_possible(); 1166 } 1167 return result; 1168 } 1169 1170 ShouldNotReachHere(); 1171 } 1172 1173 class PostMCRemSetClearClosure: public HeapRegionClosure { 1174 G1CollectedHeap* _g1h; 1175 ModRefBarrierSet* _mr_bs; 1176 public: 1177 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1178 _g1h(g1h), _mr_bs(mr_bs) {} 1179 1180 bool doHeapRegion(HeapRegion* r) { 1181 HeapRegionRemSet* hrrs = r->rem_set(); 1182 1183 if (r->continuesHumongous()) { 1184 // We'll assert that the strong code root list and RSet is empty 1185 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1186 assert(hrrs->occupied() == 0, "RSet should be empty"); 1187 return false; 1188 } 1189 1190 _g1h->reset_gc_time_stamps(r); 1191 hrrs->clear(); 1192 // You might think here that we could clear just the cards 1193 // corresponding to the used region. But no: if we leave a dirty card 1194 // in a region we might allocate into, then it would prevent that card 1195 // from being enqueued, and cause it to be missed. 1196 // Re: the performance cost: we shouldn't be doing full GC anyway! 1197 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1198 1199 return false; 1200 } 1201 }; 1202 1203 void G1CollectedHeap::clear_rsets_post_compaction() { 1204 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1205 heap_region_iterate(&rs_clear); 1206 } 1207 1208 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1209 G1CollectedHeap* _g1h; 1210 UpdateRSOopClosure _cl; 1211 int _worker_i; 1212 public: 1213 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1214 _cl(g1->g1_rem_set(), worker_i), 1215 _worker_i(worker_i), 1216 _g1h(g1) 1217 { } 1218 1219 bool doHeapRegion(HeapRegion* r) { 1220 if (!r->continuesHumongous()) { 1221 _cl.set_from(r); 1222 r->oop_iterate(&_cl); 1223 } 1224 return false; 1225 } 1226 }; 1227 1228 class ParRebuildRSTask: public AbstractGangTask { 1229 G1CollectedHeap* _g1; 1230 public: 1231 ParRebuildRSTask(G1CollectedHeap* g1) 1232 : AbstractGangTask("ParRebuildRSTask"), 1233 _g1(g1) 1234 { } 1235 1236 void work(uint worker_id) { 1237 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1238 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1239 _g1->workers()->active_workers(), 1240 HeapRegion::RebuildRSClaimValue); 1241 } 1242 }; 1243 1244 class PostCompactionPrinterClosure: public HeapRegionClosure { 1245 private: 1246 G1HRPrinter* _hr_printer; 1247 public: 1248 bool doHeapRegion(HeapRegion* hr) { 1249 assert(!hr->is_young(), "not expecting to find young regions"); 1250 // We only generate output for non-empty regions. 1251 if (!hr->is_empty()) { 1252 if (!hr->isHumongous()) { 1253 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1254 } else if (hr->startsHumongous()) { 1255 if (hr->region_num() == 1) { 1256 // single humongous region 1257 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1258 } else { 1259 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1260 } 1261 } else { 1262 assert(hr->continuesHumongous(), "only way to get here"); 1263 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1264 } 1265 } 1266 return false; 1267 } 1268 1269 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1270 : _hr_printer(hr_printer) { } 1271 }; 1272 1273 void G1CollectedHeap::print_hrs_post_compaction() { 1274 PostCompactionPrinterClosure cl(hr_printer()); 1275 heap_region_iterate(&cl); 1276 } 1277 1278 bool G1CollectedHeap::do_collection(bool explicit_gc, 1279 bool clear_all_soft_refs, 1280 size_t word_size) { 1281 assert_at_safepoint(true /* should_be_vm_thread */); 1282 1283 if (GC_locker::check_active_before_gc()) { 1284 return false; 1285 } 1286 1287 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1288 gc_timer->register_gc_start(); 1289 1290 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1291 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1292 1293 SvcGCMarker sgcm(SvcGCMarker::FULL); 1294 ResourceMark rm; 1295 1296 print_heap_before_gc(); 1297 trace_heap_before_gc(gc_tracer); 1298 1299 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes(); 1300 1301 HRSPhaseSetter x(HRSPhaseFullGC); 1302 verify_region_sets_optional(); 1303 1304 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1305 collector_policy()->should_clear_all_soft_refs(); 1306 1307 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1308 1309 { 1310 IsGCActiveMark x; 1311 1312 // Timing 1313 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1314 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1315 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1316 1317 { 1318 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1319 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1320 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1321 1322 double start = os::elapsedTime(); 1323 g1_policy()->record_full_collection_start(); 1324 1325 // Note: When we have a more flexible GC logging framework that 1326 // allows us to add optional attributes to a GC log record we 1327 // could consider timing and reporting how long we wait in the 1328 // following two methods. 1329 wait_while_free_regions_coming(); 1330 // If we start the compaction before the CM threads finish 1331 // scanning the root regions we might trip them over as we'll 1332 // be moving objects / updating references. So let's wait until 1333 // they are done. By telling them to abort, they should complete 1334 // early. 1335 _cm->root_regions()->abort(); 1336 _cm->root_regions()->wait_until_scan_finished(); 1337 append_secondary_free_list_if_not_empty_with_lock(); 1338 1339 gc_prologue(true); 1340 increment_total_collections(true /* full gc */); 1341 increment_old_marking_cycles_started(); 1342 1343 assert(used() == recalculate_used(), "Should be equal"); 1344 1345 verify_before_gc(); 1346 1347 pre_full_gc_dump(gc_timer); 1348 1349 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1350 1351 // Disable discovery and empty the discovered lists 1352 // for the CM ref processor. 1353 ref_processor_cm()->disable_discovery(); 1354 ref_processor_cm()->abandon_partial_discovery(); 1355 ref_processor_cm()->verify_no_references_recorded(); 1356 1357 // Abandon current iterations of concurrent marking and concurrent 1358 // refinement, if any are in progress. We have to do this before 1359 // wait_until_scan_finished() below. 1360 concurrent_mark()->abort(); 1361 1362 // Make sure we'll choose a new allocation region afterwards. 1363 release_mutator_alloc_region(); 1364 abandon_gc_alloc_regions(); 1365 g1_rem_set()->cleanupHRRS(); 1366 1367 // We should call this after we retire any currently active alloc 1368 // regions so that all the ALLOC / RETIRE events are generated 1369 // before the start GC event. 1370 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1371 1372 // We may have added regions to the current incremental collection 1373 // set between the last GC or pause and now. We need to clear the 1374 // incremental collection set and then start rebuilding it afresh 1375 // after this full GC. 1376 abandon_collection_set(g1_policy()->inc_cset_head()); 1377 g1_policy()->clear_incremental_cset(); 1378 g1_policy()->stop_incremental_cset_building(); 1379 1380 tear_down_region_sets(false /* free_list_only */); 1381 g1_policy()->set_gcs_are_young(true); 1382 1383 // See the comments in g1CollectedHeap.hpp and 1384 // G1CollectedHeap::ref_processing_init() about 1385 // how reference processing currently works in G1. 1386 1387 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1388 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1389 1390 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1391 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1392 1393 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1394 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1395 1396 // Do collection work 1397 { 1398 HandleMark hm; // Discard invalid handles created during gc 1399 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1400 } 1401 1402 assert(free_regions() == 0, "we should not have added any free regions"); 1403 rebuild_region_sets(false /* free_list_only */); 1404 1405 // Enqueue any discovered reference objects that have 1406 // not been removed from the discovered lists. 1407 ref_processor_stw()->enqueue_discovered_references(); 1408 1409 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1410 1411 MemoryService::track_memory_usage(); 1412 1413 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1414 ref_processor_stw()->verify_no_references_recorded(); 1415 1416 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1417 ClassLoaderDataGraph::purge(); 1418 MetaspaceAux::verify_metrics(); 1419 1420 // Note: since we've just done a full GC, concurrent 1421 // marking is no longer active. Therefore we need not 1422 // re-enable reference discovery for the CM ref processor. 1423 // That will be done at the start of the next marking cycle. 1424 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1425 ref_processor_cm()->verify_no_references_recorded(); 1426 1427 reset_gc_time_stamp(); 1428 // Since everything potentially moved, we will clear all remembered 1429 // sets, and clear all cards. Later we will rebuild remembered 1430 // sets. We will also reset the GC time stamps of the regions. 1431 clear_rsets_post_compaction(); 1432 check_gc_time_stamps(); 1433 1434 // Resize the heap if necessary. 1435 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1436 1437 if (_hr_printer.is_active()) { 1438 // We should do this after we potentially resize the heap so 1439 // that all the COMMIT / UNCOMMIT events are generated before 1440 // the end GC event. 1441 1442 print_hrs_post_compaction(); 1443 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1444 } 1445 1446 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1447 if (hot_card_cache->use_cache()) { 1448 hot_card_cache->reset_card_counts(); 1449 hot_card_cache->reset_hot_cache(); 1450 } 1451 1452 // Rebuild remembered sets of all regions. 1453 if (G1CollectedHeap::use_parallel_gc_threads()) { 1454 uint n_workers = 1455 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1456 workers()->active_workers(), 1457 Threads::number_of_non_daemon_threads()); 1458 assert(UseDynamicNumberOfGCThreads || 1459 n_workers == workers()->total_workers(), 1460 "If not dynamic should be using all the workers"); 1461 workers()->set_active_workers(n_workers); 1462 // Set parallel threads in the heap (_n_par_threads) only 1463 // before a parallel phase and always reset it to 0 after 1464 // the phase so that the number of parallel threads does 1465 // no get carried forward to a serial phase where there 1466 // may be code that is "possibly_parallel". 1467 set_par_threads(n_workers); 1468 1469 ParRebuildRSTask rebuild_rs_task(this); 1470 assert(check_heap_region_claim_values( 1471 HeapRegion::InitialClaimValue), "sanity check"); 1472 assert(UseDynamicNumberOfGCThreads || 1473 workers()->active_workers() == workers()->total_workers(), 1474 "Unless dynamic should use total workers"); 1475 // Use the most recent number of active workers 1476 assert(workers()->active_workers() > 0, 1477 "Active workers not properly set"); 1478 set_par_threads(workers()->active_workers()); 1479 workers()->run_task(&rebuild_rs_task); 1480 set_par_threads(0); 1481 assert(check_heap_region_claim_values( 1482 HeapRegion::RebuildRSClaimValue), "sanity check"); 1483 reset_heap_region_claim_values(); 1484 } else { 1485 RebuildRSOutOfRegionClosure rebuild_rs(this); 1486 heap_region_iterate(&rebuild_rs); 1487 } 1488 1489 // Rebuild the strong code root lists for each region 1490 rebuild_strong_code_roots(); 1491 1492 if (true) { // FIXME 1493 MetaspaceGC::compute_new_size(); 1494 } 1495 1496 #ifdef TRACESPINNING 1497 ParallelTaskTerminator::print_termination_counts(); 1498 #endif 1499 1500 // Discard all rset updates 1501 JavaThread::dirty_card_queue_set().abandon_logs(); 1502 assert(!G1DeferredRSUpdate 1503 || (G1DeferredRSUpdate && 1504 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1505 1506 _young_list->reset_sampled_info(); 1507 // At this point there should be no regions in the 1508 // entire heap tagged as young. 1509 assert(check_young_list_empty(true /* check_heap */), 1510 "young list should be empty at this point"); 1511 1512 // Update the number of full collections that have been completed. 1513 increment_old_marking_cycles_completed(false /* concurrent */); 1514 1515 _hrs.verify_optional(); 1516 verify_region_sets_optional(); 1517 1518 verify_after_gc(); 1519 1520 // Start a new incremental collection set for the next pause 1521 assert(g1_policy()->collection_set() == NULL, "must be"); 1522 g1_policy()->start_incremental_cset_building(); 1523 1524 // Clear the _cset_fast_test bitmap in anticipation of adding 1525 // regions to the incremental collection set for the next 1526 // evacuation pause. 1527 clear_cset_fast_test(); 1528 1529 init_mutator_alloc_region(); 1530 1531 double end = os::elapsedTime(); 1532 g1_policy()->record_full_collection_end(); 1533 1534 if (G1Log::fine()) { 1535 g1_policy()->print_heap_transition(); 1536 } 1537 1538 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1539 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1540 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1541 // before any GC notifications are raised. 1542 g1mm()->update_sizes(); 1543 1544 gc_epilogue(true); 1545 } 1546 1547 if (G1Log::finer()) { 1548 g1_policy()->print_detailed_heap_transition(true /* full */); 1549 } 1550 1551 print_heap_after_gc(); 1552 trace_heap_after_gc(gc_tracer); 1553 1554 post_full_gc_dump(gc_timer); 1555 1556 gc_timer->register_gc_end(); 1557 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1558 } 1559 1560 return true; 1561 } 1562 1563 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1564 // do_collection() will return whether it succeeded in performing 1565 // the GC. Currently, there is no facility on the 1566 // do_full_collection() API to notify the caller than the collection 1567 // did not succeed (e.g., because it was locked out by the GC 1568 // locker). So, right now, we'll ignore the return value. 1569 bool dummy = do_collection(true, /* explicit_gc */ 1570 clear_all_soft_refs, 1571 0 /* word_size */); 1572 } 1573 1574 // This code is mostly copied from TenuredGeneration. 1575 void 1576 G1CollectedHeap:: 1577 resize_if_necessary_after_full_collection(size_t word_size) { 1578 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check"); 1579 1580 // Include the current allocation, if any, and bytes that will be 1581 // pre-allocated to support collections, as "used". 1582 const size_t used_after_gc = used(); 1583 const size_t capacity_after_gc = capacity(); 1584 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1585 1586 // This is enforced in arguments.cpp. 1587 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1588 "otherwise the code below doesn't make sense"); 1589 1590 // We don't have floating point command-line arguments 1591 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1592 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1593 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1594 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1595 1596 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1597 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1598 1599 // We have to be careful here as these two calculations can overflow 1600 // 32-bit size_t's. 1601 double used_after_gc_d = (double) used_after_gc; 1602 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1603 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1604 1605 // Let's make sure that they are both under the max heap size, which 1606 // by default will make them fit into a size_t. 1607 double desired_capacity_upper_bound = (double) max_heap_size; 1608 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1609 desired_capacity_upper_bound); 1610 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1611 desired_capacity_upper_bound); 1612 1613 // We can now safely turn them into size_t's. 1614 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1615 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1616 1617 // This assert only makes sense here, before we adjust them 1618 // with respect to the min and max heap size. 1619 assert(minimum_desired_capacity <= maximum_desired_capacity, 1620 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1621 "maximum_desired_capacity = "SIZE_FORMAT, 1622 minimum_desired_capacity, maximum_desired_capacity)); 1623 1624 // Should not be greater than the heap max size. No need to adjust 1625 // it with respect to the heap min size as it's a lower bound (i.e., 1626 // we'll try to make the capacity larger than it, not smaller). 1627 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1628 // Should not be less than the heap min size. No need to adjust it 1629 // with respect to the heap max size as it's an upper bound (i.e., 1630 // we'll try to make the capacity smaller than it, not greater). 1631 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1632 1633 if (capacity_after_gc < minimum_desired_capacity) { 1634 // Don't expand unless it's significant 1635 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1636 ergo_verbose4(ErgoHeapSizing, 1637 "attempt heap expansion", 1638 ergo_format_reason("capacity lower than " 1639 "min desired capacity after Full GC") 1640 ergo_format_byte("capacity") 1641 ergo_format_byte("occupancy") 1642 ergo_format_byte_perc("min desired capacity"), 1643 capacity_after_gc, used_after_gc, 1644 minimum_desired_capacity, (double) MinHeapFreeRatio); 1645 expand(expand_bytes); 1646 1647 // No expansion, now see if we want to shrink 1648 } else if (capacity_after_gc > maximum_desired_capacity) { 1649 // Capacity too large, compute shrinking size 1650 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1651 ergo_verbose4(ErgoHeapSizing, 1652 "attempt heap shrinking", 1653 ergo_format_reason("capacity higher than " 1654 "max desired capacity after Full GC") 1655 ergo_format_byte("capacity") 1656 ergo_format_byte("occupancy") 1657 ergo_format_byte_perc("max desired capacity"), 1658 capacity_after_gc, used_after_gc, 1659 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1660 shrink(shrink_bytes); 1661 } 1662 } 1663 1664 1665 HeapWord* 1666 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1667 bool* succeeded) { 1668 assert_at_safepoint(true /* should_be_vm_thread */); 1669 1670 *succeeded = true; 1671 // Let's attempt the allocation first. 1672 HeapWord* result = 1673 attempt_allocation_at_safepoint(word_size, 1674 false /* expect_null_mutator_alloc_region */); 1675 if (result != NULL) { 1676 assert(*succeeded, "sanity"); 1677 return result; 1678 } 1679 1680 // In a G1 heap, we're supposed to keep allocation from failing by 1681 // incremental pauses. Therefore, at least for now, we'll favor 1682 // expansion over collection. (This might change in the future if we can 1683 // do something smarter than full collection to satisfy a failed alloc.) 1684 result = expand_and_allocate(word_size); 1685 if (result != NULL) { 1686 assert(*succeeded, "sanity"); 1687 return result; 1688 } 1689 1690 // Expansion didn't work, we'll try to do a Full GC. 1691 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1692 false, /* clear_all_soft_refs */ 1693 word_size); 1694 if (!gc_succeeded) { 1695 *succeeded = false; 1696 return NULL; 1697 } 1698 1699 // Retry the allocation 1700 result = attempt_allocation_at_safepoint(word_size, 1701 true /* expect_null_mutator_alloc_region */); 1702 if (result != NULL) { 1703 assert(*succeeded, "sanity"); 1704 return result; 1705 } 1706 1707 // Then, try a Full GC that will collect all soft references. 1708 gc_succeeded = do_collection(false, /* explicit_gc */ 1709 true, /* clear_all_soft_refs */ 1710 word_size); 1711 if (!gc_succeeded) { 1712 *succeeded = false; 1713 return NULL; 1714 } 1715 1716 // Retry the allocation once more 1717 result = attempt_allocation_at_safepoint(word_size, 1718 true /* expect_null_mutator_alloc_region */); 1719 if (result != NULL) { 1720 assert(*succeeded, "sanity"); 1721 return result; 1722 } 1723 1724 assert(!collector_policy()->should_clear_all_soft_refs(), 1725 "Flag should have been handled and cleared prior to this point"); 1726 1727 // What else? We might try synchronous finalization later. If the total 1728 // space available is large enough for the allocation, then a more 1729 // complete compaction phase than we've tried so far might be 1730 // appropriate. 1731 assert(*succeeded, "sanity"); 1732 return NULL; 1733 } 1734 1735 // Attempting to expand the heap sufficiently 1736 // to support an allocation of the given "word_size". If 1737 // successful, perform the allocation and return the address of the 1738 // allocated block, or else "NULL". 1739 1740 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1741 assert_at_safepoint(true /* should_be_vm_thread */); 1742 1743 verify_region_sets_optional(); 1744 1745 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1746 ergo_verbose1(ErgoHeapSizing, 1747 "attempt heap expansion", 1748 ergo_format_reason("allocation request failed") 1749 ergo_format_byte("allocation request"), 1750 word_size * HeapWordSize); 1751 if (expand(expand_bytes)) { 1752 _hrs.verify_optional(); 1753 verify_region_sets_optional(); 1754 return attempt_allocation_at_safepoint(word_size, 1755 false /* expect_null_mutator_alloc_region */); 1756 } 1757 return NULL; 1758 } 1759 1760 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1761 HeapWord* new_end) { 1762 assert(old_end != new_end, "don't call this otherwise"); 1763 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1764 1765 // Update the committed mem region. 1766 _g1_committed.set_end(new_end); 1767 // Tell the card table about the update. 1768 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1769 // Tell the BOT about the update. 1770 _bot_shared->resize(_g1_committed.word_size()); 1771 // Tell the hot card cache about the update 1772 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1773 } 1774 1775 bool G1CollectedHeap::expand(size_t expand_bytes) { 1776 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1777 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1778 HeapRegion::GrainBytes); 1779 ergo_verbose2(ErgoHeapSizing, 1780 "expand the heap", 1781 ergo_format_byte("requested expansion amount") 1782 ergo_format_byte("attempted expansion amount"), 1783 expand_bytes, aligned_expand_bytes); 1784 1785 if (_g1_storage.uncommitted_size() == 0) { 1786 ergo_verbose0(ErgoHeapSizing, 1787 "did not expand the heap", 1788 ergo_format_reason("heap already fully expanded")); 1789 return false; 1790 } 1791 1792 // First commit the memory. 1793 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1794 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1795 if (successful) { 1796 // Then propagate this update to the necessary data structures. 1797 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1798 update_committed_space(old_end, new_end); 1799 1800 FreeRegionList expansion_list("Local Expansion List"); 1801 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1802 assert(mr.start() == old_end, "post-condition"); 1803 // mr might be a smaller region than what was requested if 1804 // expand_by() was unable to allocate the HeapRegion instances 1805 assert(mr.end() <= new_end, "post-condition"); 1806 1807 size_t actual_expand_bytes = mr.byte_size(); 1808 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1809 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1810 "post-condition"); 1811 if (actual_expand_bytes < aligned_expand_bytes) { 1812 // We could not expand _hrs to the desired size. In this case we 1813 // need to shrink the committed space accordingly. 1814 assert(mr.end() < new_end, "invariant"); 1815 1816 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1817 // First uncommit the memory. 1818 _g1_storage.shrink_by(diff_bytes); 1819 // Then propagate this update to the necessary data structures. 1820 update_committed_space(new_end, mr.end()); 1821 } 1822 _free_list.add_as_tail(&expansion_list); 1823 1824 if (_hr_printer.is_active()) { 1825 HeapWord* curr = mr.start(); 1826 while (curr < mr.end()) { 1827 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1828 _hr_printer.commit(curr, curr_end); 1829 curr = curr_end; 1830 } 1831 assert(curr == mr.end(), "post-condition"); 1832 } 1833 g1_policy()->record_new_heap_size(n_regions()); 1834 } else { 1835 ergo_verbose0(ErgoHeapSizing, 1836 "did not expand the heap", 1837 ergo_format_reason("heap expansion operation failed")); 1838 // The expansion of the virtual storage space was unsuccessful. 1839 // Let's see if it was because we ran out of swap. 1840 if (G1ExitOnExpansionFailure && 1841 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1842 // We had head room... 1843 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1844 } 1845 } 1846 return successful; 1847 } 1848 1849 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1850 size_t aligned_shrink_bytes = 1851 ReservedSpace::page_align_size_down(shrink_bytes); 1852 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1853 HeapRegion::GrainBytes); 1854 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1855 1856 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1857 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1858 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1859 1860 ergo_verbose3(ErgoHeapSizing, 1861 "shrink the heap", 1862 ergo_format_byte("requested shrinking amount") 1863 ergo_format_byte("aligned shrinking amount") 1864 ergo_format_byte("attempted shrinking amount"), 1865 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1866 if (num_regions_removed > 0) { 1867 _g1_storage.shrink_by(shrunk_bytes); 1868 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1869 1870 if (_hr_printer.is_active()) { 1871 HeapWord* curr = old_end; 1872 while (curr > new_end) { 1873 HeapWord* curr_end = curr; 1874 curr -= HeapRegion::GrainWords; 1875 _hr_printer.uncommit(curr, curr_end); 1876 } 1877 } 1878 1879 _expansion_regions += num_regions_removed; 1880 update_committed_space(old_end, new_end); 1881 HeapRegionRemSet::shrink_heap(n_regions()); 1882 g1_policy()->record_new_heap_size(n_regions()); 1883 } else { 1884 ergo_verbose0(ErgoHeapSizing, 1885 "did not shrink the heap", 1886 ergo_format_reason("heap shrinking operation failed")); 1887 } 1888 } 1889 1890 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1891 verify_region_sets_optional(); 1892 1893 // We should only reach here at the end of a Full GC which means we 1894 // should not not be holding to any GC alloc regions. The method 1895 // below will make sure of that and do any remaining clean up. 1896 abandon_gc_alloc_regions(); 1897 1898 // Instead of tearing down / rebuilding the free lists here, we 1899 // could instead use the remove_all_pending() method on free_list to 1900 // remove only the ones that we need to remove. 1901 tear_down_region_sets(true /* free_list_only */); 1902 shrink_helper(shrink_bytes); 1903 rebuild_region_sets(true /* free_list_only */); 1904 1905 _hrs.verify_optional(); 1906 verify_region_sets_optional(); 1907 } 1908 1909 // Public methods. 1910 1911 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1912 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1913 #endif // _MSC_VER 1914 1915 1916 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1917 SharedHeap(policy_), 1918 _g1_policy(policy_), 1919 _dirty_card_queue_set(false), 1920 _into_cset_dirty_card_queue_set(false), 1921 _is_alive_closure_cm(this), 1922 _is_alive_closure_stw(this), 1923 _ref_processor_cm(NULL), 1924 _ref_processor_stw(NULL), 1925 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1926 _bot_shared(NULL), 1927 _evac_failure_scan_stack(NULL), 1928 _mark_in_progress(false), 1929 _cg1r(NULL), _summary_bytes_used(0), 1930 _g1mm(NULL), 1931 _refine_cte_cl(NULL), 1932 _full_collection(false), 1933 _free_list("Master Free List"), 1934 _secondary_free_list("Secondary Free List"), 1935 _old_set("Old Set"), 1936 _humongous_set("Master Humongous Set"), 1937 _free_regions_coming(false), 1938 _young_list(new YoungList(this)), 1939 _gc_time_stamp(0), 1940 _retained_old_gc_alloc_region(NULL), 1941 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1942 _old_plab_stats(OldPLABSize, PLABWeight), 1943 _expand_heap_after_alloc_failure(true), 1944 _surviving_young_words(NULL), 1945 _old_marking_cycles_started(0), 1946 _old_marking_cycles_completed(0), 1947 _concurrent_cycle_started(false), 1948 _in_cset_fast_test(NULL), 1949 _in_cset_fast_test_base(NULL), 1950 _dirty_cards_region_list(NULL), 1951 _worker_cset_start_region(NULL), 1952 _worker_cset_start_region_time_stamp(NULL), 1953 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1954 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1955 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1956 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1957 1958 _g1h = this; 1959 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1960 vm_exit_during_initialization("Failed necessary allocation."); 1961 } 1962 1963 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1964 1965 int n_queues = MAX2((int)ParallelGCThreads, 1); 1966 _task_queues = new RefToScanQueueSet(n_queues); 1967 1968 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1969 assert(n_rem_sets > 0, "Invariant."); 1970 1971 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1972 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1973 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1974 1975 for (int i = 0; i < n_queues; i++) { 1976 RefToScanQueue* q = new RefToScanQueue(); 1977 q->initialize(); 1978 _task_queues->register_queue(i, q); 1979 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1980 } 1981 clear_cset_start_regions(); 1982 1983 // Initialize the G1EvacuationFailureALot counters and flags. 1984 NOT_PRODUCT(reset_evacuation_should_fail();) 1985 1986 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1987 } 1988 1989 jint G1CollectedHeap::initialize() { 1990 CollectedHeap::pre_initialize(); 1991 os::enable_vtime(); 1992 1993 G1Log::init(); 1994 1995 // Necessary to satisfy locking discipline assertions. 1996 1997 MutexLocker x(Heap_lock); 1998 1999 // We have to initialize the printer before committing the heap, as 2000 // it will be used then. 2001 _hr_printer.set_active(G1PrintHeapRegions); 2002 2003 // While there are no constraints in the GC code that HeapWordSize 2004 // be any particular value, there are multiple other areas in the 2005 // system which believe this to be true (e.g. oop->object_size in some 2006 // cases incorrectly returns the size in wordSize units rather than 2007 // HeapWordSize). 2008 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2009 2010 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2011 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2012 size_t heap_alignment = collector_policy()->heap_alignment(); 2013 2014 // Ensure that the sizes are properly aligned. 2015 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2016 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2017 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2018 2019 _cg1r = new ConcurrentG1Refine(this); 2020 2021 // Reserve the maximum. 2022 2023 // When compressed oops are enabled, the preferred heap base 2024 // is calculated by subtracting the requested size from the 2025 // 32Gb boundary and using the result as the base address for 2026 // heap reservation. If the requested size is not aligned to 2027 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2028 // into the ReservedHeapSpace constructor) then the actual 2029 // base of the reserved heap may end up differing from the 2030 // address that was requested (i.e. the preferred heap base). 2031 // If this happens then we could end up using a non-optimal 2032 // compressed oops mode. 2033 2034 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2035 heap_alignment); 2036 2037 // It is important to do this in a way such that concurrent readers can't 2038 // temporarily think something is in the heap. (I've actually seen this 2039 // happen in asserts: DLD.) 2040 _reserved.set_word_size(0); 2041 _reserved.set_start((HeapWord*)heap_rs.base()); 2042 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2043 2044 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2045 2046 // Create the gen rem set (and barrier set) for the entire reserved region. 2047 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2048 set_barrier_set(rem_set()->bs()); 2049 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2050 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2051 return JNI_ENOMEM; 2052 } 2053 2054 // Also create a G1 rem set. 2055 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2056 2057 // Carve out the G1 part of the heap. 2058 2059 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2060 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2061 g1_rs.size()/HeapWordSize); 2062 2063 _g1_storage.initialize(g1_rs, 0); 2064 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2065 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2066 (HeapWord*) _g1_reserved.end()); 2067 assert(_hrs.max_length() == _expansion_regions, 2068 err_msg("max length: %u expansion regions: %u", 2069 _hrs.max_length(), _expansion_regions)); 2070 2071 // Do later initialization work for concurrent refinement. 2072 _cg1r->init(); 2073 2074 // 6843694 - ensure that the maximum region index can fit 2075 // in the remembered set structures. 2076 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2077 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2078 2079 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2080 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2081 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2082 "too many cards per region"); 2083 2084 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1); 2085 2086 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2087 heap_word_size(init_byte_size)); 2088 2089 _g1h = this; 2090 2091 _in_cset_fast_test_length = max_regions(); 2092 _in_cset_fast_test_base = 2093 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC); 2094 2095 // We're biasing _in_cset_fast_test to avoid subtracting the 2096 // beginning of the heap every time we want to index; basically 2097 // it's the same with what we do with the card table. 2098 _in_cset_fast_test = _in_cset_fast_test_base - 2099 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes); 2100 2101 // Clear the _cset_fast_test bitmap in anticipation of adding 2102 // regions to the incremental collection set for the first 2103 // evacuation pause. 2104 clear_cset_fast_test(); 2105 2106 // Create the ConcurrentMark data structure and thread. 2107 // (Must do this late, so that "max_regions" is defined.) 2108 _cm = new ConcurrentMark(this, heap_rs); 2109 if (_cm == NULL || !_cm->completed_initialization()) { 2110 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2111 return JNI_ENOMEM; 2112 } 2113 _cmThread = _cm->cmThread(); 2114 2115 // Initialize the from_card cache structure of HeapRegionRemSet. 2116 HeapRegionRemSet::init_heap(max_regions()); 2117 2118 // Now expand into the initial heap size. 2119 if (!expand(init_byte_size)) { 2120 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2121 return JNI_ENOMEM; 2122 } 2123 2124 // Perform any initialization actions delegated to the policy. 2125 g1_policy()->init(); 2126 2127 _refine_cte_cl = 2128 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(), 2129 g1_rem_set(), 2130 concurrent_g1_refine()); 2131 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 2132 2133 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2134 SATB_Q_FL_lock, 2135 G1SATBProcessCompletedThreshold, 2136 Shared_SATB_Q_lock); 2137 2138 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2139 DirtyCardQ_FL_lock, 2140 concurrent_g1_refine()->yellow_zone(), 2141 concurrent_g1_refine()->red_zone(), 2142 Shared_DirtyCardQ_lock); 2143 2144 if (G1DeferredRSUpdate) { 2145 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2146 DirtyCardQ_FL_lock, 2147 -1, // never trigger processing 2148 -1, // no limit on length 2149 Shared_DirtyCardQ_lock, 2150 &JavaThread::dirty_card_queue_set()); 2151 } 2152 2153 // Initialize the card queue set used to hold cards containing 2154 // references into the collection set. 2155 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, 2156 DirtyCardQ_FL_lock, 2157 -1, // never trigger processing 2158 -1, // no limit on length 2159 Shared_DirtyCardQ_lock, 2160 &JavaThread::dirty_card_queue_set()); 2161 2162 // In case we're keeping closure specialization stats, initialize those 2163 // counts and that mechanism. 2164 SpecializationStats::clear(); 2165 2166 // Here we allocate the dummy full region that is required by the 2167 // G1AllocRegion class. If we don't pass an address in the reserved 2168 // space here, lots of asserts fire. 2169 2170 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2171 _g1_reserved.start()); 2172 // We'll re-use the same region whether the alloc region will 2173 // require BOT updates or not and, if it doesn't, then a non-young 2174 // region will complain that it cannot support allocations without 2175 // BOT updates. So we'll tag the dummy region as young to avoid that. 2176 dummy_region->set_young(); 2177 // Make sure it's full. 2178 dummy_region->set_top(dummy_region->end()); 2179 G1AllocRegion::setup(this, dummy_region); 2180 2181 init_mutator_alloc_region(); 2182 2183 // Do create of the monitoring and management support so that 2184 // values in the heap have been properly initialized. 2185 _g1mm = new G1MonitoringSupport(this); 2186 2187 return JNI_OK; 2188 } 2189 2190 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2191 return HeapRegion::max_region_size(); 2192 } 2193 2194 void G1CollectedHeap::ref_processing_init() { 2195 // Reference processing in G1 currently works as follows: 2196 // 2197 // * There are two reference processor instances. One is 2198 // used to record and process discovered references 2199 // during concurrent marking; the other is used to 2200 // record and process references during STW pauses 2201 // (both full and incremental). 2202 // * Both ref processors need to 'span' the entire heap as 2203 // the regions in the collection set may be dotted around. 2204 // 2205 // * For the concurrent marking ref processor: 2206 // * Reference discovery is enabled at initial marking. 2207 // * Reference discovery is disabled and the discovered 2208 // references processed etc during remarking. 2209 // * Reference discovery is MT (see below). 2210 // * Reference discovery requires a barrier (see below). 2211 // * Reference processing may or may not be MT 2212 // (depending on the value of ParallelRefProcEnabled 2213 // and ParallelGCThreads). 2214 // * A full GC disables reference discovery by the CM 2215 // ref processor and abandons any entries on it's 2216 // discovered lists. 2217 // 2218 // * For the STW processor: 2219 // * Non MT discovery is enabled at the start of a full GC. 2220 // * Processing and enqueueing during a full GC is non-MT. 2221 // * During a full GC, references are processed after marking. 2222 // 2223 // * Discovery (may or may not be MT) is enabled at the start 2224 // of an incremental evacuation pause. 2225 // * References are processed near the end of a STW evacuation pause. 2226 // * For both types of GC: 2227 // * Discovery is atomic - i.e. not concurrent. 2228 // * Reference discovery will not need a barrier. 2229 2230 SharedHeap::ref_processing_init(); 2231 MemRegion mr = reserved_region(); 2232 2233 // Concurrent Mark ref processor 2234 _ref_processor_cm = 2235 new ReferenceProcessor(mr, // span 2236 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2237 // mt processing 2238 (int) ParallelGCThreads, 2239 // degree of mt processing 2240 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2241 // mt discovery 2242 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2243 // degree of mt discovery 2244 false, 2245 // Reference discovery is not atomic 2246 &_is_alive_closure_cm, 2247 // is alive closure 2248 // (for efficiency/performance) 2249 true); 2250 // Setting next fields of discovered 2251 // lists requires a barrier. 2252 2253 // STW ref processor 2254 _ref_processor_stw = 2255 new ReferenceProcessor(mr, // span 2256 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2257 // mt processing 2258 MAX2((int)ParallelGCThreads, 1), 2259 // degree of mt processing 2260 (ParallelGCThreads > 1), 2261 // mt discovery 2262 MAX2((int)ParallelGCThreads, 1), 2263 // degree of mt discovery 2264 true, 2265 // Reference discovery is atomic 2266 &_is_alive_closure_stw, 2267 // is alive closure 2268 // (for efficiency/performance) 2269 false); 2270 // Setting next fields of discovered 2271 // lists requires a barrier. 2272 } 2273 2274 size_t G1CollectedHeap::capacity() const { 2275 return _g1_committed.byte_size(); 2276 } 2277 2278 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2279 assert(!hr->continuesHumongous(), "pre-condition"); 2280 hr->reset_gc_time_stamp(); 2281 if (hr->startsHumongous()) { 2282 uint first_index = hr->hrs_index() + 1; 2283 uint last_index = hr->last_hc_index(); 2284 for (uint i = first_index; i < last_index; i += 1) { 2285 HeapRegion* chr = region_at(i); 2286 assert(chr->continuesHumongous(), "sanity"); 2287 chr->reset_gc_time_stamp(); 2288 } 2289 } 2290 } 2291 2292 #ifndef PRODUCT 2293 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2294 private: 2295 unsigned _gc_time_stamp; 2296 bool _failures; 2297 2298 public: 2299 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2300 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2301 2302 virtual bool doHeapRegion(HeapRegion* hr) { 2303 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2304 if (_gc_time_stamp != region_gc_time_stamp) { 2305 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2306 "expected %d", HR_FORMAT_PARAMS(hr), 2307 region_gc_time_stamp, _gc_time_stamp); 2308 _failures = true; 2309 } 2310 return false; 2311 } 2312 2313 bool failures() { return _failures; } 2314 }; 2315 2316 void G1CollectedHeap::check_gc_time_stamps() { 2317 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2318 heap_region_iterate(&cl); 2319 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2320 } 2321 #endif // PRODUCT 2322 2323 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2324 DirtyCardQueue* into_cset_dcq, 2325 bool concurrent, 2326 int worker_i) { 2327 // Clean cards in the hot card cache 2328 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2329 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2330 2331 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2332 int n_completed_buffers = 0; 2333 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2334 n_completed_buffers++; 2335 } 2336 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2337 dcqs.clear_n_completed_buffers(); 2338 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2339 } 2340 2341 2342 // Computes the sum of the storage used by the various regions. 2343 2344 size_t G1CollectedHeap::used() const { 2345 assert(Heap_lock->owner() != NULL, 2346 "Should be owned on this thread's behalf."); 2347 size_t result = _summary_bytes_used; 2348 // Read only once in case it is set to NULL concurrently 2349 HeapRegion* hr = _mutator_alloc_region.get(); 2350 if (hr != NULL) 2351 result += hr->used(); 2352 return result; 2353 } 2354 2355 size_t G1CollectedHeap::used_unlocked() const { 2356 size_t result = _summary_bytes_used; 2357 return result; 2358 } 2359 2360 class SumUsedClosure: public HeapRegionClosure { 2361 size_t _used; 2362 public: 2363 SumUsedClosure() : _used(0) {} 2364 bool doHeapRegion(HeapRegion* r) { 2365 if (!r->continuesHumongous()) { 2366 _used += r->used(); 2367 } 2368 return false; 2369 } 2370 size_t result() { return _used; } 2371 }; 2372 2373 size_t G1CollectedHeap::recalculate_used() const { 2374 SumUsedClosure blk; 2375 heap_region_iterate(&blk); 2376 return blk.result(); 2377 } 2378 2379 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2380 switch (cause) { 2381 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2382 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2383 case GCCause::_g1_humongous_allocation: return true; 2384 default: return false; 2385 } 2386 } 2387 2388 #ifndef PRODUCT 2389 void G1CollectedHeap::allocate_dummy_regions() { 2390 // Let's fill up most of the region 2391 size_t word_size = HeapRegion::GrainWords - 1024; 2392 // And as a result the region we'll allocate will be humongous. 2393 guarantee(isHumongous(word_size), "sanity"); 2394 2395 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2396 // Let's use the existing mechanism for the allocation 2397 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2398 if (dummy_obj != NULL) { 2399 MemRegion mr(dummy_obj, word_size); 2400 CollectedHeap::fill_with_object(mr); 2401 } else { 2402 // If we can't allocate once, we probably cannot allocate 2403 // again. Let's get out of the loop. 2404 break; 2405 } 2406 } 2407 } 2408 #endif // !PRODUCT 2409 2410 void G1CollectedHeap::increment_old_marking_cycles_started() { 2411 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2412 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2413 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2414 _old_marking_cycles_started, _old_marking_cycles_completed)); 2415 2416 _old_marking_cycles_started++; 2417 } 2418 2419 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2420 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2421 2422 // We assume that if concurrent == true, then the caller is a 2423 // concurrent thread that was joined the Suspendible Thread 2424 // Set. If there's ever a cheap way to check this, we should add an 2425 // assert here. 2426 2427 // Given that this method is called at the end of a Full GC or of a 2428 // concurrent cycle, and those can be nested (i.e., a Full GC can 2429 // interrupt a concurrent cycle), the number of full collections 2430 // completed should be either one (in the case where there was no 2431 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2432 // behind the number of full collections started. 2433 2434 // This is the case for the inner caller, i.e. a Full GC. 2435 assert(concurrent || 2436 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2437 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2438 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2439 "is inconsistent with _old_marking_cycles_completed = %u", 2440 _old_marking_cycles_started, _old_marking_cycles_completed)); 2441 2442 // This is the case for the outer caller, i.e. the concurrent cycle. 2443 assert(!concurrent || 2444 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2445 err_msg("for outer caller (concurrent cycle): " 2446 "_old_marking_cycles_started = %u " 2447 "is inconsistent with _old_marking_cycles_completed = %u", 2448 _old_marking_cycles_started, _old_marking_cycles_completed)); 2449 2450 _old_marking_cycles_completed += 1; 2451 2452 // We need to clear the "in_progress" flag in the CM thread before 2453 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2454 // is set) so that if a waiter requests another System.gc() it doesn't 2455 // incorrectly see that a marking cycle is still in progress. 2456 if (concurrent) { 2457 _cmThread->clear_in_progress(); 2458 } 2459 2460 // This notify_all() will ensure that a thread that called 2461 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2462 // and it's waiting for a full GC to finish will be woken up. It is 2463 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2464 FullGCCount_lock->notify_all(); 2465 } 2466 2467 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2468 _concurrent_cycle_started = true; 2469 _gc_timer_cm->register_gc_start(start_time); 2470 2471 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2472 trace_heap_before_gc(_gc_tracer_cm); 2473 } 2474 2475 void G1CollectedHeap::register_concurrent_cycle_end() { 2476 if (_concurrent_cycle_started) { 2477 if (_cm->has_aborted()) { 2478 _gc_tracer_cm->report_concurrent_mode_failure(); 2479 } 2480 2481 _gc_timer_cm->register_gc_end(); 2482 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2483 2484 _concurrent_cycle_started = false; 2485 } 2486 } 2487 2488 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2489 if (_concurrent_cycle_started) { 2490 trace_heap_after_gc(_gc_tracer_cm); 2491 } 2492 } 2493 2494 G1YCType G1CollectedHeap::yc_type() { 2495 bool is_young = g1_policy()->gcs_are_young(); 2496 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2497 bool is_during_mark = mark_in_progress(); 2498 2499 if (is_initial_mark) { 2500 return InitialMark; 2501 } else if (is_during_mark) { 2502 return DuringMark; 2503 } else if (is_young) { 2504 return Normal; 2505 } else { 2506 return Mixed; 2507 } 2508 } 2509 2510 void G1CollectedHeap::collect(GCCause::Cause cause) { 2511 assert_heap_not_locked(); 2512 2513 unsigned int gc_count_before; 2514 unsigned int old_marking_count_before; 2515 bool retry_gc; 2516 2517 do { 2518 retry_gc = false; 2519 2520 { 2521 MutexLocker ml(Heap_lock); 2522 2523 // Read the GC count while holding the Heap_lock 2524 gc_count_before = total_collections(); 2525 old_marking_count_before = _old_marking_cycles_started; 2526 } 2527 2528 if (should_do_concurrent_full_gc(cause)) { 2529 // Schedule an initial-mark evacuation pause that will start a 2530 // concurrent cycle. We're setting word_size to 0 which means that 2531 // we are not requesting a post-GC allocation. 2532 VM_G1IncCollectionPause op(gc_count_before, 2533 0, /* word_size */ 2534 true, /* should_initiate_conc_mark */ 2535 g1_policy()->max_pause_time_ms(), 2536 cause); 2537 2538 VMThread::execute(&op); 2539 if (!op.pause_succeeded()) { 2540 if (old_marking_count_before == _old_marking_cycles_started) { 2541 retry_gc = op.should_retry_gc(); 2542 } else { 2543 // A Full GC happened while we were trying to schedule the 2544 // initial-mark GC. No point in starting a new cycle given 2545 // that the whole heap was collected anyway. 2546 } 2547 2548 if (retry_gc) { 2549 if (GC_locker::is_active_and_needs_gc()) { 2550 GC_locker::stall_until_clear(); 2551 } 2552 } 2553 } 2554 } else { 2555 if (cause == GCCause::_gc_locker 2556 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2557 2558 // Schedule a standard evacuation pause. We're setting word_size 2559 // to 0 which means that we are not requesting a post-GC allocation. 2560 VM_G1IncCollectionPause op(gc_count_before, 2561 0, /* word_size */ 2562 false, /* should_initiate_conc_mark */ 2563 g1_policy()->max_pause_time_ms(), 2564 cause); 2565 VMThread::execute(&op); 2566 } else { 2567 // Schedule a Full GC. 2568 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2569 VMThread::execute(&op); 2570 } 2571 } 2572 } while (retry_gc); 2573 } 2574 2575 bool G1CollectedHeap::is_in(const void* p) const { 2576 if (_g1_committed.contains(p)) { 2577 // Given that we know that p is in the committed space, 2578 // heap_region_containing_raw() should successfully 2579 // return the containing region. 2580 HeapRegion* hr = heap_region_containing_raw(p); 2581 return hr->is_in(p); 2582 } else { 2583 return false; 2584 } 2585 } 2586 2587 // Iteration functions. 2588 2589 // Iterates an OopClosure over all ref-containing fields of objects 2590 // within a HeapRegion. 2591 2592 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2593 MemRegion _mr; 2594 ExtendedOopClosure* _cl; 2595 public: 2596 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2597 : _mr(mr), _cl(cl) {} 2598 bool doHeapRegion(HeapRegion* r) { 2599 if (!r->continuesHumongous()) { 2600 r->oop_iterate(_cl); 2601 } 2602 return false; 2603 } 2604 }; 2605 2606 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2607 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2608 heap_region_iterate(&blk); 2609 } 2610 2611 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2612 IterateOopClosureRegionClosure blk(mr, cl); 2613 heap_region_iterate(&blk); 2614 } 2615 2616 // Iterates an ObjectClosure over all objects within a HeapRegion. 2617 2618 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2619 ObjectClosure* _cl; 2620 public: 2621 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2622 bool doHeapRegion(HeapRegion* r) { 2623 if (! r->continuesHumongous()) { 2624 r->object_iterate(_cl); 2625 } 2626 return false; 2627 } 2628 }; 2629 2630 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2631 IterateObjectClosureRegionClosure blk(cl); 2632 heap_region_iterate(&blk); 2633 } 2634 2635 // Calls a SpaceClosure on a HeapRegion. 2636 2637 class SpaceClosureRegionClosure: public HeapRegionClosure { 2638 SpaceClosure* _cl; 2639 public: 2640 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2641 bool doHeapRegion(HeapRegion* r) { 2642 _cl->do_space(r); 2643 return false; 2644 } 2645 }; 2646 2647 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2648 SpaceClosureRegionClosure blk(cl); 2649 heap_region_iterate(&blk); 2650 } 2651 2652 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2653 _hrs.iterate(cl); 2654 } 2655 2656 void 2657 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2658 uint worker_id, 2659 uint no_of_par_workers, 2660 jint claim_value) { 2661 const uint regions = n_regions(); 2662 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2663 no_of_par_workers : 2664 1); 2665 assert(UseDynamicNumberOfGCThreads || 2666 no_of_par_workers == workers()->total_workers(), 2667 "Non dynamic should use fixed number of workers"); 2668 // try to spread out the starting points of the workers 2669 const HeapRegion* start_hr = 2670 start_region_for_worker(worker_id, no_of_par_workers); 2671 const uint start_index = start_hr->hrs_index(); 2672 2673 // each worker will actually look at all regions 2674 for (uint count = 0; count < regions; ++count) { 2675 const uint index = (start_index + count) % regions; 2676 assert(0 <= index && index < regions, "sanity"); 2677 HeapRegion* r = region_at(index); 2678 // we'll ignore "continues humongous" regions (we'll process them 2679 // when we come across their corresponding "start humongous" 2680 // region) and regions already claimed 2681 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2682 continue; 2683 } 2684 // OK, try to claim it 2685 if (r->claimHeapRegion(claim_value)) { 2686 // success! 2687 assert(!r->continuesHumongous(), "sanity"); 2688 if (r->startsHumongous()) { 2689 // If the region is "starts humongous" we'll iterate over its 2690 // "continues humongous" first; in fact we'll do them 2691 // first. The order is important. In on case, calling the 2692 // closure on the "starts humongous" region might de-allocate 2693 // and clear all its "continues humongous" regions and, as a 2694 // result, we might end up processing them twice. So, we'll do 2695 // them first (notice: most closures will ignore them anyway) and 2696 // then we'll do the "starts humongous" region. 2697 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2698 HeapRegion* chr = region_at(ch_index); 2699 2700 // if the region has already been claimed or it's not 2701 // "continues humongous" we're done 2702 if (chr->claim_value() == claim_value || 2703 !chr->continuesHumongous()) { 2704 break; 2705 } 2706 2707 // No one should have claimed it directly. We can given 2708 // that we claimed its "starts humongous" region. 2709 assert(chr->claim_value() != claim_value, "sanity"); 2710 assert(chr->humongous_start_region() == r, "sanity"); 2711 2712 if (chr->claimHeapRegion(claim_value)) { 2713 // we should always be able to claim it; no one else should 2714 // be trying to claim this region 2715 2716 bool res2 = cl->doHeapRegion(chr); 2717 assert(!res2, "Should not abort"); 2718 2719 // Right now, this holds (i.e., no closure that actually 2720 // does something with "continues humongous" regions 2721 // clears them). We might have to weaken it in the future, 2722 // but let's leave these two asserts here for extra safety. 2723 assert(chr->continuesHumongous(), "should still be the case"); 2724 assert(chr->humongous_start_region() == r, "sanity"); 2725 } else { 2726 guarantee(false, "we should not reach here"); 2727 } 2728 } 2729 } 2730 2731 assert(!r->continuesHumongous(), "sanity"); 2732 bool res = cl->doHeapRegion(r); 2733 assert(!res, "Should not abort"); 2734 } 2735 } 2736 } 2737 2738 class ResetClaimValuesClosure: public HeapRegionClosure { 2739 public: 2740 bool doHeapRegion(HeapRegion* r) { 2741 r->set_claim_value(HeapRegion::InitialClaimValue); 2742 return false; 2743 } 2744 }; 2745 2746 void G1CollectedHeap::reset_heap_region_claim_values() { 2747 ResetClaimValuesClosure blk; 2748 heap_region_iterate(&blk); 2749 } 2750 2751 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2752 ResetClaimValuesClosure blk; 2753 collection_set_iterate(&blk); 2754 } 2755 2756 #ifdef ASSERT 2757 // This checks whether all regions in the heap have the correct claim 2758 // value. I also piggy-backed on this a check to ensure that the 2759 // humongous_start_region() information on "continues humongous" 2760 // regions is correct. 2761 2762 class CheckClaimValuesClosure : public HeapRegionClosure { 2763 private: 2764 jint _claim_value; 2765 uint _failures; 2766 HeapRegion* _sh_region; 2767 2768 public: 2769 CheckClaimValuesClosure(jint claim_value) : 2770 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2771 bool doHeapRegion(HeapRegion* r) { 2772 if (r->claim_value() != _claim_value) { 2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2774 "claim value = %d, should be %d", 2775 HR_FORMAT_PARAMS(r), 2776 r->claim_value(), _claim_value); 2777 ++_failures; 2778 } 2779 if (!r->isHumongous()) { 2780 _sh_region = NULL; 2781 } else if (r->startsHumongous()) { 2782 _sh_region = r; 2783 } else if (r->continuesHumongous()) { 2784 if (r->humongous_start_region() != _sh_region) { 2785 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2786 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2787 HR_FORMAT_PARAMS(r), 2788 r->humongous_start_region(), 2789 _sh_region); 2790 ++_failures; 2791 } 2792 } 2793 return false; 2794 } 2795 uint failures() { return _failures; } 2796 }; 2797 2798 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2799 CheckClaimValuesClosure cl(claim_value); 2800 heap_region_iterate(&cl); 2801 return cl.failures() == 0; 2802 } 2803 2804 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2805 private: 2806 jint _claim_value; 2807 uint _failures; 2808 2809 public: 2810 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2811 _claim_value(claim_value), _failures(0) { } 2812 2813 uint failures() { return _failures; } 2814 2815 bool doHeapRegion(HeapRegion* hr) { 2816 assert(hr->in_collection_set(), "how?"); 2817 assert(!hr->isHumongous(), "H-region in CSet"); 2818 if (hr->claim_value() != _claim_value) { 2819 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2820 "claim value = %d, should be %d", 2821 HR_FORMAT_PARAMS(hr), 2822 hr->claim_value(), _claim_value); 2823 _failures += 1; 2824 } 2825 return false; 2826 } 2827 }; 2828 2829 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2830 CheckClaimValuesInCSetHRClosure cl(claim_value); 2831 collection_set_iterate(&cl); 2832 return cl.failures() == 0; 2833 } 2834 #endif // ASSERT 2835 2836 // Clear the cached CSet starting regions and (more importantly) 2837 // the time stamps. Called when we reset the GC time stamp. 2838 void G1CollectedHeap::clear_cset_start_regions() { 2839 assert(_worker_cset_start_region != NULL, "sanity"); 2840 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2841 2842 int n_queues = MAX2((int)ParallelGCThreads, 1); 2843 for (int i = 0; i < n_queues; i++) { 2844 _worker_cset_start_region[i] = NULL; 2845 _worker_cset_start_region_time_stamp[i] = 0; 2846 } 2847 } 2848 2849 // Given the id of a worker, obtain or calculate a suitable 2850 // starting region for iterating over the current collection set. 2851 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) { 2852 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2853 2854 HeapRegion* result = NULL; 2855 unsigned gc_time_stamp = get_gc_time_stamp(); 2856 2857 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2858 // Cached starting region for current worker was set 2859 // during the current pause - so it's valid. 2860 // Note: the cached starting heap region may be NULL 2861 // (when the collection set is empty). 2862 result = _worker_cset_start_region[worker_i]; 2863 assert(result == NULL || result->in_collection_set(), "sanity"); 2864 return result; 2865 } 2866 2867 // The cached entry was not valid so let's calculate 2868 // a suitable starting heap region for this worker. 2869 2870 // We want the parallel threads to start their collection 2871 // set iteration at different collection set regions to 2872 // avoid contention. 2873 // If we have: 2874 // n collection set regions 2875 // p threads 2876 // Then thread t will start at region floor ((t * n) / p) 2877 2878 result = g1_policy()->collection_set(); 2879 if (G1CollectedHeap::use_parallel_gc_threads()) { 2880 uint cs_size = g1_policy()->cset_region_length(); 2881 uint active_workers = workers()->active_workers(); 2882 assert(UseDynamicNumberOfGCThreads || 2883 active_workers == workers()->total_workers(), 2884 "Unless dynamic should use total workers"); 2885 2886 uint end_ind = (cs_size * worker_i) / active_workers; 2887 uint start_ind = 0; 2888 2889 if (worker_i > 0 && 2890 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2891 // Previous workers starting region is valid 2892 // so let's iterate from there 2893 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2894 result = _worker_cset_start_region[worker_i - 1]; 2895 } 2896 2897 for (uint i = start_ind; i < end_ind; i++) { 2898 result = result->next_in_collection_set(); 2899 } 2900 } 2901 2902 // Note: the calculated starting heap region may be NULL 2903 // (when the collection set is empty). 2904 assert(result == NULL || result->in_collection_set(), "sanity"); 2905 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2906 "should be updated only once per pause"); 2907 _worker_cset_start_region[worker_i] = result; 2908 OrderAccess::storestore(); 2909 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2910 return result; 2911 } 2912 2913 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2914 uint no_of_par_workers) { 2915 uint worker_num = 2916 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2917 assert(UseDynamicNumberOfGCThreads || 2918 no_of_par_workers == workers()->total_workers(), 2919 "Non dynamic should use fixed number of workers"); 2920 const uint start_index = n_regions() * worker_i / worker_num; 2921 return region_at(start_index); 2922 } 2923 2924 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2925 HeapRegion* r = g1_policy()->collection_set(); 2926 while (r != NULL) { 2927 HeapRegion* next = r->next_in_collection_set(); 2928 if (cl->doHeapRegion(r)) { 2929 cl->incomplete(); 2930 return; 2931 } 2932 r = next; 2933 } 2934 } 2935 2936 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2937 HeapRegionClosure *cl) { 2938 if (r == NULL) { 2939 // The CSet is empty so there's nothing to do. 2940 return; 2941 } 2942 2943 assert(r->in_collection_set(), 2944 "Start region must be a member of the collection set."); 2945 HeapRegion* cur = r; 2946 while (cur != NULL) { 2947 HeapRegion* next = cur->next_in_collection_set(); 2948 if (cl->doHeapRegion(cur) && false) { 2949 cl->incomplete(); 2950 return; 2951 } 2952 cur = next; 2953 } 2954 cur = g1_policy()->collection_set(); 2955 while (cur != r) { 2956 HeapRegion* next = cur->next_in_collection_set(); 2957 if (cl->doHeapRegion(cur) && false) { 2958 cl->incomplete(); 2959 return; 2960 } 2961 cur = next; 2962 } 2963 } 2964 2965 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2966 return n_regions() > 0 ? region_at(0) : NULL; 2967 } 2968 2969 2970 Space* G1CollectedHeap::space_containing(const void* addr) const { 2971 Space* res = heap_region_containing(addr); 2972 return res; 2973 } 2974 2975 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2976 Space* sp = space_containing(addr); 2977 if (sp != NULL) { 2978 return sp->block_start(addr); 2979 } 2980 return NULL; 2981 } 2982 2983 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2984 Space* sp = space_containing(addr); 2985 assert(sp != NULL, "block_size of address outside of heap"); 2986 return sp->block_size(addr); 2987 } 2988 2989 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2990 Space* sp = space_containing(addr); 2991 return sp->block_is_obj(addr); 2992 } 2993 2994 bool G1CollectedHeap::supports_tlab_allocation() const { 2995 return true; 2996 } 2997 2998 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2999 return HeapRegion::GrainBytes; 3000 } 3001 3002 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 3003 // Return the remaining space in the cur alloc region, but not less than 3004 // the min TLAB size. 3005 3006 // Also, this value can be at most the humongous object threshold, 3007 // since we can't allow tlabs to grow big enough to accommodate 3008 // humongous objects. 3009 3010 HeapRegion* hr = _mutator_alloc_region.get(); 3011 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize; 3012 if (hr == NULL) { 3013 return max_tlab_size; 3014 } else { 3015 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size); 3016 } 3017 } 3018 3019 size_t G1CollectedHeap::max_capacity() const { 3020 return _g1_reserved.byte_size(); 3021 } 3022 3023 jlong G1CollectedHeap::millis_since_last_gc() { 3024 // assert(false, "NYI"); 3025 return 0; 3026 } 3027 3028 void G1CollectedHeap::prepare_for_verify() { 3029 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3030 ensure_parsability(false); 3031 } 3032 g1_rem_set()->prepare_for_verify(); 3033 } 3034 3035 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3036 VerifyOption vo) { 3037 switch (vo) { 3038 case VerifyOption_G1UsePrevMarking: 3039 return hr->obj_allocated_since_prev_marking(obj); 3040 case VerifyOption_G1UseNextMarking: 3041 return hr->obj_allocated_since_next_marking(obj); 3042 case VerifyOption_G1UseMarkWord: 3043 return false; 3044 default: 3045 ShouldNotReachHere(); 3046 } 3047 return false; // keep some compilers happy 3048 } 3049 3050 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3051 switch (vo) { 3052 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3053 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3054 case VerifyOption_G1UseMarkWord: return NULL; 3055 default: ShouldNotReachHere(); 3056 } 3057 return NULL; // keep some compilers happy 3058 } 3059 3060 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3061 switch (vo) { 3062 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3063 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3064 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3065 default: ShouldNotReachHere(); 3066 } 3067 return false; // keep some compilers happy 3068 } 3069 3070 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3071 switch (vo) { 3072 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3073 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3074 case VerifyOption_G1UseMarkWord: return "NONE"; 3075 default: ShouldNotReachHere(); 3076 } 3077 return NULL; // keep some compilers happy 3078 } 3079 3080 class VerifyRootsClosure: public OopClosure { 3081 private: 3082 G1CollectedHeap* _g1h; 3083 VerifyOption _vo; 3084 bool _failures; 3085 public: 3086 // _vo == UsePrevMarking -> use "prev" marking information, 3087 // _vo == UseNextMarking -> use "next" marking information, 3088 // _vo == UseMarkWord -> use mark word from object header. 3089 VerifyRootsClosure(VerifyOption vo) : 3090 _g1h(G1CollectedHeap::heap()), 3091 _vo(vo), 3092 _failures(false) { } 3093 3094 bool failures() { return _failures; } 3095 3096 template <class T> void do_oop_nv(T* p) { 3097 T heap_oop = oopDesc::load_heap_oop(p); 3098 if (!oopDesc::is_null(heap_oop)) { 3099 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3100 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3101 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3102 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3103 if (_vo == VerifyOption_G1UseMarkWord) { 3104 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3105 } 3106 obj->print_on(gclog_or_tty); 3107 _failures = true; 3108 } 3109 } 3110 } 3111 3112 void do_oop(oop* p) { do_oop_nv(p); } 3113 void do_oop(narrowOop* p) { do_oop_nv(p); } 3114 }; 3115 3116 class G1VerifyCodeRootOopClosure: public OopClosure { 3117 G1CollectedHeap* _g1h; 3118 OopClosure* _root_cl; 3119 nmethod* _nm; 3120 VerifyOption _vo; 3121 bool _failures; 3122 3123 template <class T> void do_oop_work(T* p) { 3124 // First verify that this root is live 3125 _root_cl->do_oop(p); 3126 3127 if (!G1VerifyHeapRegionCodeRoots) { 3128 // We're not verifying the code roots attached to heap region. 3129 return; 3130 } 3131 3132 // Don't check the code roots during marking verification in a full GC 3133 if (_vo == VerifyOption_G1UseMarkWord) { 3134 return; 3135 } 3136 3137 // Now verify that the current nmethod (which contains p) is 3138 // in the code root list of the heap region containing the 3139 // object referenced by p. 3140 3141 T heap_oop = oopDesc::load_heap_oop(p); 3142 if (!oopDesc::is_null(heap_oop)) { 3143 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3144 3145 // Now fetch the region containing the object 3146 HeapRegion* hr = _g1h->heap_region_containing(obj); 3147 HeapRegionRemSet* hrrs = hr->rem_set(); 3148 // Verify that the strong code root list for this region 3149 // contains the nmethod 3150 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3151 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3152 "from nmethod "PTR_FORMAT" not in strong " 3153 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3154 p, _nm, hr->bottom(), hr->end()); 3155 _failures = true; 3156 } 3157 } 3158 } 3159 3160 public: 3161 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3162 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3163 3164 void do_oop(oop* p) { do_oop_work(p); } 3165 void do_oop(narrowOop* p) { do_oop_work(p); } 3166 3167 void set_nmethod(nmethod* nm) { _nm = nm; } 3168 bool failures() { return _failures; } 3169 }; 3170 3171 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3172 G1VerifyCodeRootOopClosure* _oop_cl; 3173 3174 public: 3175 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3176 _oop_cl(oop_cl) {} 3177 3178 void do_code_blob(CodeBlob* cb) { 3179 nmethod* nm = cb->as_nmethod_or_null(); 3180 if (nm != NULL) { 3181 _oop_cl->set_nmethod(nm); 3182 nm->oops_do(_oop_cl); 3183 } 3184 } 3185 }; 3186 3187 class YoungRefCounterClosure : public OopClosure { 3188 G1CollectedHeap* _g1h; 3189 int _count; 3190 public: 3191 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3192 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3193 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3194 3195 int count() { return _count; } 3196 void reset_count() { _count = 0; }; 3197 }; 3198 3199 class VerifyKlassClosure: public KlassClosure { 3200 YoungRefCounterClosure _young_ref_counter_closure; 3201 OopClosure *_oop_closure; 3202 public: 3203 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3204 void do_klass(Klass* k) { 3205 k->oops_do(_oop_closure); 3206 3207 _young_ref_counter_closure.reset_count(); 3208 k->oops_do(&_young_ref_counter_closure); 3209 if (_young_ref_counter_closure.count() > 0) { 3210 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k)); 3211 } 3212 } 3213 }; 3214 3215 class VerifyLivenessOopClosure: public OopClosure { 3216 G1CollectedHeap* _g1h; 3217 VerifyOption _vo; 3218 public: 3219 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3220 _g1h(g1h), _vo(vo) 3221 { } 3222 void do_oop(narrowOop *p) { do_oop_work(p); } 3223 void do_oop( oop *p) { do_oop_work(p); } 3224 3225 template <class T> void do_oop_work(T *p) { 3226 oop obj = oopDesc::load_decode_heap_oop(p); 3227 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3228 "Dead object referenced by a not dead object"); 3229 } 3230 }; 3231 3232 class VerifyObjsInRegionClosure: public ObjectClosure { 3233 private: 3234 G1CollectedHeap* _g1h; 3235 size_t _live_bytes; 3236 HeapRegion *_hr; 3237 VerifyOption _vo; 3238 public: 3239 // _vo == UsePrevMarking -> use "prev" marking information, 3240 // _vo == UseNextMarking -> use "next" marking information, 3241 // _vo == UseMarkWord -> use mark word from object header. 3242 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3243 : _live_bytes(0), _hr(hr), _vo(vo) { 3244 _g1h = G1CollectedHeap::heap(); 3245 } 3246 void do_object(oop o) { 3247 VerifyLivenessOopClosure isLive(_g1h, _vo); 3248 assert(o != NULL, "Huh?"); 3249 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3250 // If the object is alive according to the mark word, 3251 // then verify that the marking information agrees. 3252 // Note we can't verify the contra-positive of the 3253 // above: if the object is dead (according to the mark 3254 // word), it may not be marked, or may have been marked 3255 // but has since became dead, or may have been allocated 3256 // since the last marking. 3257 if (_vo == VerifyOption_G1UseMarkWord) { 3258 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3259 } 3260 3261 o->oop_iterate_no_header(&isLive); 3262 if (!_hr->obj_allocated_since_prev_marking(o)) { 3263 size_t obj_size = o->size(); // Make sure we don't overflow 3264 _live_bytes += (obj_size * HeapWordSize); 3265 } 3266 } 3267 } 3268 size_t live_bytes() { return _live_bytes; } 3269 }; 3270 3271 class PrintObjsInRegionClosure : public ObjectClosure { 3272 HeapRegion *_hr; 3273 G1CollectedHeap *_g1; 3274 public: 3275 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3276 _g1 = G1CollectedHeap::heap(); 3277 }; 3278 3279 void do_object(oop o) { 3280 if (o != NULL) { 3281 HeapWord *start = (HeapWord *) o; 3282 size_t word_sz = o->size(); 3283 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3284 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3285 (void*) o, word_sz, 3286 _g1->isMarkedPrev(o), 3287 _g1->isMarkedNext(o), 3288 _hr->obj_allocated_since_prev_marking(o)); 3289 HeapWord *end = start + word_sz; 3290 HeapWord *cur; 3291 int *val; 3292 for (cur = start; cur < end; cur++) { 3293 val = (int *) cur; 3294 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3295 } 3296 } 3297 } 3298 }; 3299 3300 class VerifyRegionClosure: public HeapRegionClosure { 3301 private: 3302 bool _par; 3303 VerifyOption _vo; 3304 bool _failures; 3305 public: 3306 // _vo == UsePrevMarking -> use "prev" marking information, 3307 // _vo == UseNextMarking -> use "next" marking information, 3308 // _vo == UseMarkWord -> use mark word from object header. 3309 VerifyRegionClosure(bool par, VerifyOption vo) 3310 : _par(par), 3311 _vo(vo), 3312 _failures(false) {} 3313 3314 bool failures() { 3315 return _failures; 3316 } 3317 3318 bool doHeapRegion(HeapRegion* r) { 3319 if (!r->continuesHumongous()) { 3320 bool failures = false; 3321 r->verify(_vo, &failures); 3322 if (failures) { 3323 _failures = true; 3324 } else { 3325 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3326 r->object_iterate(¬_dead_yet_cl); 3327 if (_vo != VerifyOption_G1UseNextMarking) { 3328 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3329 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3330 "max_live_bytes "SIZE_FORMAT" " 3331 "< calculated "SIZE_FORMAT, 3332 r->bottom(), r->end(), 3333 r->max_live_bytes(), 3334 not_dead_yet_cl.live_bytes()); 3335 _failures = true; 3336 } 3337 } else { 3338 // When vo == UseNextMarking we cannot currently do a sanity 3339 // check on the live bytes as the calculation has not been 3340 // finalized yet. 3341 } 3342 } 3343 } 3344 return false; // stop the region iteration if we hit a failure 3345 } 3346 }; 3347 3348 // This is the task used for parallel verification of the heap regions 3349 3350 class G1ParVerifyTask: public AbstractGangTask { 3351 private: 3352 G1CollectedHeap* _g1h; 3353 VerifyOption _vo; 3354 bool _failures; 3355 3356 public: 3357 // _vo == UsePrevMarking -> use "prev" marking information, 3358 // _vo == UseNextMarking -> use "next" marking information, 3359 // _vo == UseMarkWord -> use mark word from object header. 3360 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3361 AbstractGangTask("Parallel verify task"), 3362 _g1h(g1h), 3363 _vo(vo), 3364 _failures(false) { } 3365 3366 bool failures() { 3367 return _failures; 3368 } 3369 3370 void work(uint worker_id) { 3371 HandleMark hm; 3372 VerifyRegionClosure blk(true, _vo); 3373 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3374 _g1h->workers()->active_workers(), 3375 HeapRegion::ParVerifyClaimValue); 3376 if (blk.failures()) { 3377 _failures = true; 3378 } 3379 } 3380 }; 3381 3382 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3383 if (SafepointSynchronize::is_at_safepoint()) { 3384 assert(Thread::current()->is_VM_thread(), 3385 "Expected to be executed serially by the VM thread at this point"); 3386 3387 if (!silent) { gclog_or_tty->print("Roots "); } 3388 VerifyRootsClosure rootsCl(vo); 3389 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3390 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3391 VerifyKlassClosure klassCl(this, &rootsCl); 3392 3393 // We apply the relevant closures to all the oops in the 3394 // system dictionary, the string table and the code cache. 3395 const int so = SO_AllClasses | SO_Strings | SO_AllCodeCache; 3396 3397 // Need cleared claim bits for the strong roots processing 3398 ClassLoaderDataGraph::clear_claimed_marks(); 3399 3400 process_strong_roots(true, // activate StrongRootsScope 3401 ScanningOption(so), // roots scanning options 3402 &rootsCl, 3403 &blobsCl, 3404 &klassCl 3405 ); 3406 3407 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3408 3409 if (vo != VerifyOption_G1UseMarkWord) { 3410 // If we're verifying during a full GC then the region sets 3411 // will have been torn down at the start of the GC. Therefore 3412 // verifying the region sets will fail. So we only verify 3413 // the region sets when not in a full GC. 3414 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3415 verify_region_sets(); 3416 } 3417 3418 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3419 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3420 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3421 "sanity check"); 3422 3423 G1ParVerifyTask task(this, vo); 3424 assert(UseDynamicNumberOfGCThreads || 3425 workers()->active_workers() == workers()->total_workers(), 3426 "If not dynamic should be using all the workers"); 3427 int n_workers = workers()->active_workers(); 3428 set_par_threads(n_workers); 3429 workers()->run_task(&task); 3430 set_par_threads(0); 3431 if (task.failures()) { 3432 failures = true; 3433 } 3434 3435 // Checks that the expected amount of parallel work was done. 3436 // The implication is that n_workers is > 0. 3437 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3438 "sanity check"); 3439 3440 reset_heap_region_claim_values(); 3441 3442 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3443 "sanity check"); 3444 } else { 3445 VerifyRegionClosure blk(false, vo); 3446 heap_region_iterate(&blk); 3447 if (blk.failures()) { 3448 failures = true; 3449 } 3450 } 3451 if (!silent) gclog_or_tty->print("RemSet "); 3452 rem_set()->verify(); 3453 3454 if (failures) { 3455 gclog_or_tty->print_cr("Heap:"); 3456 // It helps to have the per-region information in the output to 3457 // help us track down what went wrong. This is why we call 3458 // print_extended_on() instead of print_on(). 3459 print_extended_on(gclog_or_tty); 3460 gclog_or_tty->print_cr(""); 3461 #ifndef PRODUCT 3462 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3463 concurrent_mark()->print_reachable("at-verification-failure", 3464 vo, false /* all */); 3465 } 3466 #endif 3467 gclog_or_tty->flush(); 3468 } 3469 guarantee(!failures, "there should not have been any failures"); 3470 } else { 3471 if (!silent) 3472 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) "); 3473 } 3474 } 3475 3476 void G1CollectedHeap::verify(bool silent) { 3477 verify(silent, VerifyOption_G1UsePrevMarking); 3478 } 3479 3480 double G1CollectedHeap::verify(bool guard, const char* msg) { 3481 double verify_time_ms = 0.0; 3482 3483 if (guard && total_collections() >= VerifyGCStartAt) { 3484 double verify_start = os::elapsedTime(); 3485 HandleMark hm; // Discard invalid handles created during verification 3486 prepare_for_verify(); 3487 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3488 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3489 } 3490 3491 return verify_time_ms; 3492 } 3493 3494 void G1CollectedHeap::verify_before_gc() { 3495 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3496 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3497 } 3498 3499 void G1CollectedHeap::verify_after_gc() { 3500 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3501 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3502 } 3503 3504 class PrintRegionClosure: public HeapRegionClosure { 3505 outputStream* _st; 3506 public: 3507 PrintRegionClosure(outputStream* st) : _st(st) {} 3508 bool doHeapRegion(HeapRegion* r) { 3509 r->print_on(_st); 3510 return false; 3511 } 3512 }; 3513 3514 void G1CollectedHeap::print_on(outputStream* st) const { 3515 st->print(" %-20s", "garbage-first heap"); 3516 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3517 capacity()/K, used_unlocked()/K); 3518 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3519 _g1_storage.low_boundary(), 3520 _g1_storage.high(), 3521 _g1_storage.high_boundary()); 3522 st->cr(); 3523 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3524 uint young_regions = _young_list->length(); 3525 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3526 (size_t) young_regions * HeapRegion::GrainBytes / K); 3527 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3528 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3529 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3530 st->cr(); 3531 MetaspaceAux::print_on(st); 3532 } 3533 3534 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3535 print_on(st); 3536 3537 // Print the per-region information. 3538 st->cr(); 3539 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3540 "HS=humongous(starts), HC=humongous(continues), " 3541 "CS=collection set, F=free, TS=gc time stamp, " 3542 "PTAMS=previous top-at-mark-start, " 3543 "NTAMS=next top-at-mark-start)"); 3544 PrintRegionClosure blk(st); 3545 heap_region_iterate(&blk); 3546 } 3547 3548 void G1CollectedHeap::print_on_error(outputStream* st) const { 3549 this->CollectedHeap::print_on_error(st); 3550 3551 if (_cm != NULL) { 3552 st->cr(); 3553 _cm->print_on_error(st); 3554 } 3555 } 3556 3557 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3558 if (G1CollectedHeap::use_parallel_gc_threads()) { 3559 workers()->print_worker_threads_on(st); 3560 } 3561 _cmThread->print_on(st); 3562 st->cr(); 3563 _cm->print_worker_threads_on(st); 3564 _cg1r->print_worker_threads_on(st); 3565 } 3566 3567 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3568 if (G1CollectedHeap::use_parallel_gc_threads()) { 3569 workers()->threads_do(tc); 3570 } 3571 tc->do_thread(_cmThread); 3572 _cg1r->threads_do(tc); 3573 } 3574 3575 void G1CollectedHeap::print_tracing_info() const { 3576 // We'll overload this to mean "trace GC pause statistics." 3577 if (TraceGen0Time || TraceGen1Time) { 3578 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3579 // to that. 3580 g1_policy()->print_tracing_info(); 3581 } 3582 if (G1SummarizeRSetStats) { 3583 g1_rem_set()->print_summary_info(); 3584 } 3585 if (G1SummarizeConcMark) { 3586 concurrent_mark()->print_summary_info(); 3587 } 3588 g1_policy()->print_yg_surv_rate_info(); 3589 SpecializationStats::print(); 3590 } 3591 3592 #ifndef PRODUCT 3593 // Helpful for debugging RSet issues. 3594 3595 class PrintRSetsClosure : public HeapRegionClosure { 3596 private: 3597 const char* _msg; 3598 size_t _occupied_sum; 3599 3600 public: 3601 bool doHeapRegion(HeapRegion* r) { 3602 HeapRegionRemSet* hrrs = r->rem_set(); 3603 size_t occupied = hrrs->occupied(); 3604 _occupied_sum += occupied; 3605 3606 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3607 HR_FORMAT_PARAMS(r)); 3608 if (occupied == 0) { 3609 gclog_or_tty->print_cr(" RSet is empty"); 3610 } else { 3611 hrrs->print(); 3612 } 3613 gclog_or_tty->print_cr("----------"); 3614 return false; 3615 } 3616 3617 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3618 gclog_or_tty->cr(); 3619 gclog_or_tty->print_cr("========================================"); 3620 gclog_or_tty->print_cr(msg); 3621 gclog_or_tty->cr(); 3622 } 3623 3624 ~PrintRSetsClosure() { 3625 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3626 gclog_or_tty->print_cr("========================================"); 3627 gclog_or_tty->cr(); 3628 } 3629 }; 3630 3631 void G1CollectedHeap::print_cset_rsets() { 3632 PrintRSetsClosure cl("Printing CSet RSets"); 3633 collection_set_iterate(&cl); 3634 } 3635 3636 void G1CollectedHeap::print_all_rsets() { 3637 PrintRSetsClosure cl("Printing All RSets");; 3638 heap_region_iterate(&cl); 3639 } 3640 #endif // PRODUCT 3641 3642 G1CollectedHeap* G1CollectedHeap::heap() { 3643 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3644 "not a garbage-first heap"); 3645 return _g1h; 3646 } 3647 3648 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3649 // always_do_update_barrier = false; 3650 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3651 // Fill TLAB's and such 3652 ensure_parsability(true); 3653 3654 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3655 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3656 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3657 } 3658 } 3659 3660 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3661 3662 if (G1SummarizeRSetStats && 3663 (G1SummarizeRSetStatsPeriod > 0) && 3664 // we are at the end of the GC. Total collections has already been increased. 3665 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3666 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3667 } 3668 3669 // FIXME: what is this about? 3670 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3671 // is set. 3672 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3673 "derived pointer present")); 3674 // always_do_update_barrier = true; 3675 3676 // We have just completed a GC. Update the soft reference 3677 // policy with the new heap occupancy 3678 Universe::update_heap_info_at_gc(); 3679 } 3680 3681 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3682 unsigned int gc_count_before, 3683 bool* succeeded, 3684 GCCause::Cause gc_cause) { 3685 assert_heap_not_locked_and_not_at_safepoint(); 3686 g1_policy()->record_stop_world_start(); 3687 VM_G1IncCollectionPause op(gc_count_before, 3688 word_size, 3689 false, /* should_initiate_conc_mark */ 3690 g1_policy()->max_pause_time_ms(), 3691 gc_cause); 3692 VMThread::execute(&op); 3693 3694 HeapWord* result = op.result(); 3695 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3696 assert(result == NULL || ret_succeeded, 3697 "the result should be NULL if the VM did not succeed"); 3698 *succeeded = ret_succeeded; 3699 3700 assert_heap_not_locked(); 3701 return result; 3702 } 3703 3704 void 3705 G1CollectedHeap::doConcurrentMark() { 3706 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3707 if (!_cmThread->in_progress()) { 3708 _cmThread->set_started(); 3709 CGC_lock->notify(); 3710 } 3711 } 3712 3713 size_t G1CollectedHeap::pending_card_num() { 3714 size_t extra_cards = 0; 3715 JavaThread *curr = Threads::first(); 3716 while (curr != NULL) { 3717 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3718 extra_cards += dcq.size(); 3719 curr = curr->next(); 3720 } 3721 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3722 size_t buffer_size = dcqs.buffer_size(); 3723 size_t buffer_num = dcqs.completed_buffers_num(); 3724 3725 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3726 // in bytes - not the number of 'entries'. We need to convert 3727 // into a number of cards. 3728 return (buffer_size * buffer_num + extra_cards) / oopSize; 3729 } 3730 3731 size_t G1CollectedHeap::cards_scanned() { 3732 return g1_rem_set()->cardsScanned(); 3733 } 3734 3735 void 3736 G1CollectedHeap::setup_surviving_young_words() { 3737 assert(_surviving_young_words == NULL, "pre-condition"); 3738 uint array_length = g1_policy()->young_cset_region_length(); 3739 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3740 if (_surviving_young_words == NULL) { 3741 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3742 "Not enough space for young surv words summary."); 3743 } 3744 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3745 #ifdef ASSERT 3746 for (uint i = 0; i < array_length; ++i) { 3747 assert( _surviving_young_words[i] == 0, "memset above" ); 3748 } 3749 #endif // !ASSERT 3750 } 3751 3752 void 3753 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3754 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3755 uint array_length = g1_policy()->young_cset_region_length(); 3756 for (uint i = 0; i < array_length; ++i) { 3757 _surviving_young_words[i] += surv_young_words[i]; 3758 } 3759 } 3760 3761 void 3762 G1CollectedHeap::cleanup_surviving_young_words() { 3763 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3764 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3765 _surviving_young_words = NULL; 3766 } 3767 3768 #ifdef ASSERT 3769 class VerifyCSetClosure: public HeapRegionClosure { 3770 public: 3771 bool doHeapRegion(HeapRegion* hr) { 3772 // Here we check that the CSet region's RSet is ready for parallel 3773 // iteration. The fields that we'll verify are only manipulated 3774 // when the region is part of a CSet and is collected. Afterwards, 3775 // we reset these fields when we clear the region's RSet (when the 3776 // region is freed) so they are ready when the region is 3777 // re-allocated. The only exception to this is if there's an 3778 // evacuation failure and instead of freeing the region we leave 3779 // it in the heap. In that case, we reset these fields during 3780 // evacuation failure handling. 3781 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3782 3783 // Here's a good place to add any other checks we'd like to 3784 // perform on CSet regions. 3785 return false; 3786 } 3787 }; 3788 #endif // ASSERT 3789 3790 #if TASKQUEUE_STATS 3791 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3792 st->print_raw_cr("GC Task Stats"); 3793 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3794 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3795 } 3796 3797 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3798 print_taskqueue_stats_hdr(st); 3799 3800 TaskQueueStats totals; 3801 const int n = workers() != NULL ? workers()->total_workers() : 1; 3802 for (int i = 0; i < n; ++i) { 3803 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3804 totals += task_queue(i)->stats; 3805 } 3806 st->print_raw("tot "); totals.print(st); st->cr(); 3807 3808 DEBUG_ONLY(totals.verify()); 3809 } 3810 3811 void G1CollectedHeap::reset_taskqueue_stats() { 3812 const int n = workers() != NULL ? workers()->total_workers() : 1; 3813 for (int i = 0; i < n; ++i) { 3814 task_queue(i)->stats.reset(); 3815 } 3816 } 3817 #endif // TASKQUEUE_STATS 3818 3819 void G1CollectedHeap::log_gc_header() { 3820 if (!G1Log::fine()) { 3821 return; 3822 } 3823 3824 gclog_or_tty->date_stamp(PrintGCDateStamps); 3825 gclog_or_tty->stamp(PrintGCTimeStamps); 3826 3827 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3828 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3829 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3830 3831 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3832 } 3833 3834 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3835 if (!G1Log::fine()) { 3836 return; 3837 } 3838 3839 if (G1Log::finer()) { 3840 if (evacuation_failed()) { 3841 gclog_or_tty->print(" (to-space exhausted)"); 3842 } 3843 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3844 g1_policy()->phase_times()->note_gc_end(); 3845 g1_policy()->phase_times()->print(pause_time_sec); 3846 g1_policy()->print_detailed_heap_transition(); 3847 } else { 3848 if (evacuation_failed()) { 3849 gclog_or_tty->print("--"); 3850 } 3851 g1_policy()->print_heap_transition(); 3852 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3853 } 3854 gclog_or_tty->flush(); 3855 } 3856 3857 bool 3858 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3859 assert_at_safepoint(true /* should_be_vm_thread */); 3860 guarantee(!is_gc_active(), "collection is not reentrant"); 3861 3862 if (GC_locker::check_active_before_gc()) { 3863 return false; 3864 } 3865 3866 _gc_timer_stw->register_gc_start(); 3867 3868 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3869 3870 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3871 ResourceMark rm; 3872 3873 print_heap_before_gc(); 3874 trace_heap_before_gc(_gc_tracer_stw); 3875 3876 HRSPhaseSetter x(HRSPhaseEvacuation); 3877 verify_region_sets_optional(); 3878 verify_dirty_young_regions(); 3879 3880 // This call will decide whether this pause is an initial-mark 3881 // pause. If it is, during_initial_mark_pause() will return true 3882 // for the duration of this pause. 3883 g1_policy()->decide_on_conc_mark_initiation(); 3884 3885 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3886 assert(!g1_policy()->during_initial_mark_pause() || 3887 g1_policy()->gcs_are_young(), "sanity"); 3888 3889 // We also do not allow mixed GCs during marking. 3890 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3891 3892 // Record whether this pause is an initial mark. When the current 3893 // thread has completed its logging output and it's safe to signal 3894 // the CM thread, the flag's value in the policy has been reset. 3895 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3896 3897 // Inner scope for scope based logging, timers, and stats collection 3898 { 3899 EvacuationInfo evacuation_info; 3900 3901 if (g1_policy()->during_initial_mark_pause()) { 3902 // We are about to start a marking cycle, so we increment the 3903 // full collection counter. 3904 increment_old_marking_cycles_started(); 3905 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3906 } 3907 3908 _gc_tracer_stw->report_yc_type(yc_type()); 3909 3910 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3911 3912 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3913 workers()->active_workers() : 1); 3914 double pause_start_sec = os::elapsedTime(); 3915 g1_policy()->phase_times()->note_gc_start(active_workers); 3916 log_gc_header(); 3917 3918 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3919 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3920 3921 // If the secondary_free_list is not empty, append it to the 3922 // free_list. No need to wait for the cleanup operation to finish; 3923 // the region allocation code will check the secondary_free_list 3924 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3925 // set, skip this step so that the region allocation code has to 3926 // get entries from the secondary_free_list. 3927 if (!G1StressConcRegionFreeing) { 3928 append_secondary_free_list_if_not_empty_with_lock(); 3929 } 3930 3931 assert(check_young_list_well_formed(), "young list should be well formed"); 3932 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3933 "sanity check"); 3934 3935 // Don't dynamically change the number of GC threads this early. A value of 3936 // 0 is used to indicate serial work. When parallel work is done, 3937 // it will be set. 3938 3939 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3940 IsGCActiveMark x; 3941 3942 gc_prologue(false); 3943 increment_total_collections(false /* full gc */); 3944 increment_gc_time_stamp(); 3945 3946 verify_before_gc(); 3947 3948 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3949 3950 // Please see comment in g1CollectedHeap.hpp and 3951 // G1CollectedHeap::ref_processing_init() to see how 3952 // reference processing currently works in G1. 3953 3954 // Enable discovery in the STW reference processor 3955 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3956 true /*verify_no_refs*/); 3957 3958 { 3959 // We want to temporarily turn off discovery by the 3960 // CM ref processor, if necessary, and turn it back on 3961 // on again later if we do. Using a scoped 3962 // NoRefDiscovery object will do this. 3963 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3964 3965 // Forget the current alloc region (we might even choose it to be part 3966 // of the collection set!). 3967 release_mutator_alloc_region(); 3968 3969 // We should call this after we retire the mutator alloc 3970 // region(s) so that all the ALLOC / RETIRE events are generated 3971 // before the start GC event. 3972 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3973 3974 // This timing is only used by the ergonomics to handle our pause target. 3975 // It is unclear why this should not include the full pause. We will 3976 // investigate this in CR 7178365. 3977 // 3978 // Preserving the old comment here if that helps the investigation: 3979 // 3980 // The elapsed time induced by the start time below deliberately elides 3981 // the possible verification above. 3982 double sample_start_time_sec = os::elapsedTime(); 3983 3984 #if YOUNG_LIST_VERBOSE 3985 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3986 _young_list->print(); 3987 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3988 #endif // YOUNG_LIST_VERBOSE 3989 3990 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3991 3992 double scan_wait_start = os::elapsedTime(); 3993 // We have to wait until the CM threads finish scanning the 3994 // root regions as it's the only way to ensure that all the 3995 // objects on them have been correctly scanned before we start 3996 // moving them during the GC. 3997 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3998 double wait_time_ms = 0.0; 3999 if (waited) { 4000 double scan_wait_end = os::elapsedTime(); 4001 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4002 } 4003 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4004 4005 #if YOUNG_LIST_VERBOSE 4006 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4007 _young_list->print(); 4008 #endif // YOUNG_LIST_VERBOSE 4009 4010 if (g1_policy()->during_initial_mark_pause()) { 4011 concurrent_mark()->checkpointRootsInitialPre(); 4012 } 4013 4014 #if YOUNG_LIST_VERBOSE 4015 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4016 _young_list->print(); 4017 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4018 #endif // YOUNG_LIST_VERBOSE 4019 4020 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4021 4022 _cm->note_start_of_gc(); 4023 // We should not verify the per-thread SATB buffers given that 4024 // we have not filtered them yet (we'll do so during the 4025 // GC). We also call this after finalize_cset() to 4026 // ensure that the CSet has been finalized. 4027 _cm->verify_no_cset_oops(true /* verify_stacks */, 4028 true /* verify_enqueued_buffers */, 4029 false /* verify_thread_buffers */, 4030 true /* verify_fingers */); 4031 4032 if (_hr_printer.is_active()) { 4033 HeapRegion* hr = g1_policy()->collection_set(); 4034 while (hr != NULL) { 4035 G1HRPrinter::RegionType type; 4036 if (!hr->is_young()) { 4037 type = G1HRPrinter::Old; 4038 } else if (hr->is_survivor()) { 4039 type = G1HRPrinter::Survivor; 4040 } else { 4041 type = G1HRPrinter::Eden; 4042 } 4043 _hr_printer.cset(hr); 4044 hr = hr->next_in_collection_set(); 4045 } 4046 } 4047 4048 #ifdef ASSERT 4049 VerifyCSetClosure cl; 4050 collection_set_iterate(&cl); 4051 #endif // ASSERT 4052 4053 setup_surviving_young_words(); 4054 4055 // Initialize the GC alloc regions. 4056 init_gc_alloc_regions(evacuation_info); 4057 4058 // Actually do the work... 4059 evacuate_collection_set(evacuation_info); 4060 4061 // We do this to mainly verify the per-thread SATB buffers 4062 // (which have been filtered by now) since we didn't verify 4063 // them earlier. No point in re-checking the stacks / enqueued 4064 // buffers given that the CSet has not changed since last time 4065 // we checked. 4066 _cm->verify_no_cset_oops(false /* verify_stacks */, 4067 false /* verify_enqueued_buffers */, 4068 true /* verify_thread_buffers */, 4069 true /* verify_fingers */); 4070 4071 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4072 g1_policy()->clear_collection_set(); 4073 4074 cleanup_surviving_young_words(); 4075 4076 // Start a new incremental collection set for the next pause. 4077 g1_policy()->start_incremental_cset_building(); 4078 4079 // Clear the _cset_fast_test bitmap in anticipation of adding 4080 // regions to the incremental collection set for the next 4081 // evacuation pause. 4082 clear_cset_fast_test(); 4083 4084 _young_list->reset_sampled_info(); 4085 4086 // Don't check the whole heap at this point as the 4087 // GC alloc regions from this pause have been tagged 4088 // as survivors and moved on to the survivor list. 4089 // Survivor regions will fail the !is_young() check. 4090 assert(check_young_list_empty(false /* check_heap */), 4091 "young list should be empty"); 4092 4093 #if YOUNG_LIST_VERBOSE 4094 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4095 _young_list->print(); 4096 #endif // YOUNG_LIST_VERBOSE 4097 4098 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4099 _young_list->first_survivor_region(), 4100 _young_list->last_survivor_region()); 4101 4102 _young_list->reset_auxilary_lists(); 4103 4104 if (evacuation_failed()) { 4105 _summary_bytes_used = recalculate_used(); 4106 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4107 for (uint i = 0; i < n_queues; i++) { 4108 if (_evacuation_failed_info_array[i].has_failed()) { 4109 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4110 } 4111 } 4112 } else { 4113 // The "used" of the the collection set have already been subtracted 4114 // when they were freed. Add in the bytes evacuated. 4115 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4116 } 4117 4118 if (g1_policy()->during_initial_mark_pause()) { 4119 // We have to do this before we notify the CM threads that 4120 // they can start working to make sure that all the 4121 // appropriate initialization is done on the CM object. 4122 concurrent_mark()->checkpointRootsInitialPost(); 4123 set_marking_started(); 4124 // Note that we don't actually trigger the CM thread at 4125 // this point. We do that later when we're sure that 4126 // the current thread has completed its logging output. 4127 } 4128 4129 allocate_dummy_regions(); 4130 4131 #if YOUNG_LIST_VERBOSE 4132 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4133 _young_list->print(); 4134 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4135 #endif // YOUNG_LIST_VERBOSE 4136 4137 init_mutator_alloc_region(); 4138 4139 { 4140 size_t expand_bytes = g1_policy()->expansion_amount(); 4141 if (expand_bytes > 0) { 4142 size_t bytes_before = capacity(); 4143 // No need for an ergo verbose message here, 4144 // expansion_amount() does this when it returns a value > 0. 4145 if (!expand(expand_bytes)) { 4146 // We failed to expand the heap so let's verify that 4147 // committed/uncommitted amount match the backing store 4148 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4149 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4150 } 4151 } 4152 } 4153 4154 // We redo the verification but now wrt to the new CSet which 4155 // has just got initialized after the previous CSet was freed. 4156 _cm->verify_no_cset_oops(true /* verify_stacks */, 4157 true /* verify_enqueued_buffers */, 4158 true /* verify_thread_buffers */, 4159 true /* verify_fingers */); 4160 _cm->note_end_of_gc(); 4161 4162 // This timing is only used by the ergonomics to handle our pause target. 4163 // It is unclear why this should not include the full pause. We will 4164 // investigate this in CR 7178365. 4165 double sample_end_time_sec = os::elapsedTime(); 4166 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4167 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4168 4169 MemoryService::track_memory_usage(); 4170 4171 // In prepare_for_verify() below we'll need to scan the deferred 4172 // update buffers to bring the RSets up-to-date if 4173 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4174 // the update buffers we'll probably need to scan cards on the 4175 // regions we just allocated to (i.e., the GC alloc 4176 // regions). However, during the last GC we called 4177 // set_saved_mark() on all the GC alloc regions, so card 4178 // scanning might skip the [saved_mark_word()...top()] area of 4179 // those regions (i.e., the area we allocated objects into 4180 // during the last GC). But it shouldn't. Given that 4181 // saved_mark_word() is conditional on whether the GC time stamp 4182 // on the region is current or not, by incrementing the GC time 4183 // stamp here we invalidate all the GC time stamps on all the 4184 // regions and saved_mark_word() will simply return top() for 4185 // all the regions. This is a nicer way of ensuring this rather 4186 // than iterating over the regions and fixing them. In fact, the 4187 // GC time stamp increment here also ensures that 4188 // saved_mark_word() will return top() between pauses, i.e., 4189 // during concurrent refinement. So we don't need the 4190 // is_gc_active() check to decided which top to use when 4191 // scanning cards (see CR 7039627). 4192 increment_gc_time_stamp(); 4193 4194 verify_after_gc(); 4195 4196 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4197 ref_processor_stw()->verify_no_references_recorded(); 4198 4199 // CM reference discovery will be re-enabled if necessary. 4200 } 4201 4202 // We should do this after we potentially expand the heap so 4203 // that all the COMMIT events are generated before the end GC 4204 // event, and after we retire the GC alloc regions so that all 4205 // RETIRE events are generated before the end GC event. 4206 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4207 4208 if (mark_in_progress()) { 4209 concurrent_mark()->update_g1_committed(); 4210 } 4211 4212 #ifdef TRACESPINNING 4213 ParallelTaskTerminator::print_termination_counts(); 4214 #endif 4215 4216 gc_epilogue(false); 4217 } 4218 4219 // Print the remainder of the GC log output. 4220 log_gc_footer(os::elapsedTime() - pause_start_sec); 4221 4222 // It is not yet to safe to tell the concurrent mark to 4223 // start as we have some optional output below. We don't want the 4224 // output from the concurrent mark thread interfering with this 4225 // logging output either. 4226 4227 _hrs.verify_optional(); 4228 verify_region_sets_optional(); 4229 4230 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4231 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4232 4233 print_heap_after_gc(); 4234 trace_heap_after_gc(_gc_tracer_stw); 4235 4236 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4237 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4238 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4239 // before any GC notifications are raised. 4240 g1mm()->update_sizes(); 4241 4242 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4243 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4244 _gc_timer_stw->register_gc_end(); 4245 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4246 } 4247 // It should now be safe to tell the concurrent mark thread to start 4248 // without its logging output interfering with the logging output 4249 // that came from the pause. 4250 4251 if (should_start_conc_mark) { 4252 // CAUTION: after the doConcurrentMark() call below, 4253 // the concurrent marking thread(s) could be running 4254 // concurrently with us. Make sure that anything after 4255 // this point does not assume that we are the only GC thread 4256 // running. Note: of course, the actual marking work will 4257 // not start until the safepoint itself is released in 4258 // ConcurrentGCThread::safepoint_desynchronize(). 4259 doConcurrentMark(); 4260 } 4261 4262 return true; 4263 } 4264 4265 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4266 { 4267 size_t gclab_word_size; 4268 switch (purpose) { 4269 case GCAllocForSurvived: 4270 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4271 break; 4272 case GCAllocForTenured: 4273 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4274 break; 4275 default: 4276 assert(false, "unknown GCAllocPurpose"); 4277 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4278 break; 4279 } 4280 4281 // Prevent humongous PLAB sizes for two reasons: 4282 // * PLABs are allocated using a similar paths as oops, but should 4283 // never be in a humongous region 4284 // * Allowing humongous PLABs needlessly churns the region free lists 4285 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4286 } 4287 4288 void G1CollectedHeap::init_mutator_alloc_region() { 4289 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4290 _mutator_alloc_region.init(); 4291 } 4292 4293 void G1CollectedHeap::release_mutator_alloc_region() { 4294 _mutator_alloc_region.release(); 4295 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4296 } 4297 4298 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4299 assert_at_safepoint(true /* should_be_vm_thread */); 4300 4301 _survivor_gc_alloc_region.init(); 4302 _old_gc_alloc_region.init(); 4303 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4304 _retained_old_gc_alloc_region = NULL; 4305 4306 // We will discard the current GC alloc region if: 4307 // a) it's in the collection set (it can happen!), 4308 // b) it's already full (no point in using it), 4309 // c) it's empty (this means that it was emptied during 4310 // a cleanup and it should be on the free list now), or 4311 // d) it's humongous (this means that it was emptied 4312 // during a cleanup and was added to the free list, but 4313 // has been subsequently used to allocate a humongous 4314 // object that may be less than the region size). 4315 if (retained_region != NULL && 4316 !retained_region->in_collection_set() && 4317 !(retained_region->top() == retained_region->end()) && 4318 !retained_region->is_empty() && 4319 !retained_region->isHumongous()) { 4320 retained_region->set_saved_mark(); 4321 // The retained region was added to the old region set when it was 4322 // retired. We have to remove it now, since we don't allow regions 4323 // we allocate to in the region sets. We'll re-add it later, when 4324 // it's retired again. 4325 _old_set.remove(retained_region); 4326 bool during_im = g1_policy()->during_initial_mark_pause(); 4327 retained_region->note_start_of_copying(during_im); 4328 _old_gc_alloc_region.set(retained_region); 4329 _hr_printer.reuse(retained_region); 4330 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4331 } 4332 } 4333 4334 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4335 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4336 _old_gc_alloc_region.count()); 4337 _survivor_gc_alloc_region.release(); 4338 // If we have an old GC alloc region to release, we'll save it in 4339 // _retained_old_gc_alloc_region. If we don't 4340 // _retained_old_gc_alloc_region will become NULL. This is what we 4341 // want either way so no reason to check explicitly for either 4342 // condition. 4343 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4344 4345 if (ResizePLAB) { 4346 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4347 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4348 } 4349 } 4350 4351 void G1CollectedHeap::abandon_gc_alloc_regions() { 4352 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4353 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4354 _retained_old_gc_alloc_region = NULL; 4355 } 4356 4357 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4358 _drain_in_progress = false; 4359 set_evac_failure_closure(cl); 4360 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4361 } 4362 4363 void G1CollectedHeap::finalize_for_evac_failure() { 4364 assert(_evac_failure_scan_stack != NULL && 4365 _evac_failure_scan_stack->length() == 0, 4366 "Postcondition"); 4367 assert(!_drain_in_progress, "Postcondition"); 4368 delete _evac_failure_scan_stack; 4369 _evac_failure_scan_stack = NULL; 4370 } 4371 4372 void G1CollectedHeap::remove_self_forwarding_pointers() { 4373 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4374 4375 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4376 4377 if (G1CollectedHeap::use_parallel_gc_threads()) { 4378 set_par_threads(); 4379 workers()->run_task(&rsfp_task); 4380 set_par_threads(0); 4381 } else { 4382 rsfp_task.work(0); 4383 } 4384 4385 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4386 4387 // Reset the claim values in the regions in the collection set. 4388 reset_cset_heap_region_claim_values(); 4389 4390 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4391 4392 // Now restore saved marks, if any. 4393 assert(_objs_with_preserved_marks.size() == 4394 _preserved_marks_of_objs.size(), "Both or none."); 4395 while (!_objs_with_preserved_marks.is_empty()) { 4396 oop obj = _objs_with_preserved_marks.pop(); 4397 markOop m = _preserved_marks_of_objs.pop(); 4398 obj->set_mark(m); 4399 } 4400 _objs_with_preserved_marks.clear(true); 4401 _preserved_marks_of_objs.clear(true); 4402 } 4403 4404 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4405 _evac_failure_scan_stack->push(obj); 4406 } 4407 4408 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4409 assert(_evac_failure_scan_stack != NULL, "precondition"); 4410 4411 while (_evac_failure_scan_stack->length() > 0) { 4412 oop obj = _evac_failure_scan_stack->pop(); 4413 _evac_failure_closure->set_region(heap_region_containing(obj)); 4414 obj->oop_iterate_backwards(_evac_failure_closure); 4415 } 4416 } 4417 4418 oop 4419 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4420 oop old) { 4421 assert(obj_in_cs(old), 4422 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4423 (HeapWord*) old)); 4424 markOop m = old->mark(); 4425 oop forward_ptr = old->forward_to_atomic(old); 4426 if (forward_ptr == NULL) { 4427 // Forward-to-self succeeded. 4428 assert(_par_scan_state != NULL, "par scan state"); 4429 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4430 uint queue_num = _par_scan_state->queue_num(); 4431 4432 _evacuation_failed = true; 4433 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4434 if (_evac_failure_closure != cl) { 4435 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4436 assert(!_drain_in_progress, 4437 "Should only be true while someone holds the lock."); 4438 // Set the global evac-failure closure to the current thread's. 4439 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4440 set_evac_failure_closure(cl); 4441 // Now do the common part. 4442 handle_evacuation_failure_common(old, m); 4443 // Reset to NULL. 4444 set_evac_failure_closure(NULL); 4445 } else { 4446 // The lock is already held, and this is recursive. 4447 assert(_drain_in_progress, "This should only be the recursive case."); 4448 handle_evacuation_failure_common(old, m); 4449 } 4450 return old; 4451 } else { 4452 // Forward-to-self failed. Either someone else managed to allocate 4453 // space for this object (old != forward_ptr) or they beat us in 4454 // self-forwarding it (old == forward_ptr). 4455 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4456 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4457 "should not be in the CSet", 4458 (HeapWord*) old, (HeapWord*) forward_ptr)); 4459 return forward_ptr; 4460 } 4461 } 4462 4463 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4464 preserve_mark_if_necessary(old, m); 4465 4466 HeapRegion* r = heap_region_containing(old); 4467 if (!r->evacuation_failed()) { 4468 r->set_evacuation_failed(true); 4469 _hr_printer.evac_failure(r); 4470 } 4471 4472 push_on_evac_failure_scan_stack(old); 4473 4474 if (!_drain_in_progress) { 4475 // prevent recursion in copy_to_survivor_space() 4476 _drain_in_progress = true; 4477 drain_evac_failure_scan_stack(); 4478 _drain_in_progress = false; 4479 } 4480 } 4481 4482 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4483 assert(evacuation_failed(), "Oversaving!"); 4484 // We want to call the "for_promotion_failure" version only in the 4485 // case of a promotion failure. 4486 if (m->must_be_preserved_for_promotion_failure(obj)) { 4487 _objs_with_preserved_marks.push(obj); 4488 _preserved_marks_of_objs.push(m); 4489 } 4490 } 4491 4492 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4493 size_t word_size) { 4494 if (purpose == GCAllocForSurvived) { 4495 HeapWord* result = survivor_attempt_allocation(word_size); 4496 if (result != NULL) { 4497 return result; 4498 } else { 4499 // Let's try to allocate in the old gen in case we can fit the 4500 // object there. 4501 return old_attempt_allocation(word_size); 4502 } 4503 } else { 4504 assert(purpose == GCAllocForTenured, "sanity"); 4505 HeapWord* result = old_attempt_allocation(word_size); 4506 if (result != NULL) { 4507 return result; 4508 } else { 4509 // Let's try to allocate in the survivors in case we can fit the 4510 // object there. 4511 return survivor_attempt_allocation(word_size); 4512 } 4513 } 4514 4515 ShouldNotReachHere(); 4516 // Trying to keep some compilers happy. 4517 return NULL; 4518 } 4519 4520 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4521 ParGCAllocBuffer(gclab_word_size), _retired(false) { } 4522 4523 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num) 4524 : _g1h(g1h), 4525 _refs(g1h->task_queue(queue_num)), 4526 _dcq(&g1h->dirty_card_queue_set()), 4527 _ct_bs(g1h->g1_barrier_set()), 4528 _g1_rem(g1h->g1_rem_set()), 4529 _hash_seed(17), _queue_num(queue_num), 4530 _term_attempts(0), 4531 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4532 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4533 _age_table(false), 4534 _strong_roots_time(0), _term_time(0), 4535 _alloc_buffer_waste(0), _undo_waste(0) { 4536 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4537 // we "sacrifice" entry 0 to keep track of surviving bytes for 4538 // non-young regions (where the age is -1) 4539 // We also add a few elements at the beginning and at the end in 4540 // an attempt to eliminate cache contention 4541 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4542 uint array_length = PADDING_ELEM_NUM + 4543 real_length + 4544 PADDING_ELEM_NUM; 4545 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4546 if (_surviving_young_words_base == NULL) 4547 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 4548 "Not enough space for young surv histo."); 4549 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4550 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4551 4552 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4553 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4554 4555 _start = os::elapsedTime(); 4556 } 4557 4558 void 4559 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4560 { 4561 st->print_raw_cr("GC Termination Stats"); 4562 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4563 " ------waste (KiB)------"); 4564 st->print_raw_cr("thr ms ms % ms % attempts" 4565 " total alloc undo"); 4566 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4567 " ------- ------- -------"); 4568 } 4569 4570 void 4571 G1ParScanThreadState::print_termination_stats(int i, 4572 outputStream* const st) const 4573 { 4574 const double elapsed_ms = elapsed_time() * 1000.0; 4575 const double s_roots_ms = strong_roots_time() * 1000.0; 4576 const double term_ms = term_time() * 1000.0; 4577 st->print_cr("%3d %9.2f %9.2f %6.2f " 4578 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4579 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4580 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4581 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4582 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4583 alloc_buffer_waste() * HeapWordSize / K, 4584 undo_waste() * HeapWordSize / K); 4585 } 4586 4587 #ifdef ASSERT 4588 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4589 assert(ref != NULL, "invariant"); 4590 assert(UseCompressedOops, "sanity"); 4591 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4592 oop p = oopDesc::load_decode_heap_oop(ref); 4593 assert(_g1h->is_in_g1_reserved(p), 4594 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4595 return true; 4596 } 4597 4598 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4599 assert(ref != NULL, "invariant"); 4600 if (has_partial_array_mask(ref)) { 4601 // Must be in the collection set--it's already been copied. 4602 oop p = clear_partial_array_mask(ref); 4603 assert(_g1h->obj_in_cs(p), 4604 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4605 } else { 4606 oop p = oopDesc::load_decode_heap_oop(ref); 4607 assert(_g1h->is_in_g1_reserved(p), 4608 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4609 } 4610 return true; 4611 } 4612 4613 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4614 if (ref.is_narrow()) { 4615 return verify_ref((narrowOop*) ref); 4616 } else { 4617 return verify_ref((oop*) ref); 4618 } 4619 } 4620 #endif // ASSERT 4621 4622 void G1ParScanThreadState::trim_queue() { 4623 assert(_evac_cl != NULL, "not set"); 4624 assert(_evac_failure_cl != NULL, "not set"); 4625 assert(_partial_scan_cl != NULL, "not set"); 4626 4627 StarTask ref; 4628 do { 4629 // Drain the overflow stack first, so other threads can steal. 4630 while (refs()->pop_overflow(ref)) { 4631 deal_with_reference(ref); 4632 } 4633 4634 while (refs()->pop_local(ref)) { 4635 deal_with_reference(ref); 4636 } 4637 } while (!refs()->is_empty()); 4638 } 4639 4640 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4641 G1ParScanThreadState* par_scan_state) : 4642 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()), 4643 _par_scan_state(par_scan_state), 4644 _worker_id(par_scan_state->queue_num()), 4645 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()), 4646 _mark_in_progress(_g1->mark_in_progress()) { } 4647 4648 template <G1Barrier barrier, bool do_mark_object> 4649 void G1ParCopyClosure<barrier, do_mark_object>::mark_object(oop obj) { 4650 #ifdef ASSERT 4651 HeapRegion* hr = _g1->heap_region_containing(obj); 4652 assert(hr != NULL, "sanity"); 4653 assert(!hr->in_collection_set(), "should not mark objects in the CSet"); 4654 #endif // ASSERT 4655 4656 // We know that the object is not moving so it's safe to read its size. 4657 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4658 } 4659 4660 template <G1Barrier barrier, bool do_mark_object> 4661 void G1ParCopyClosure<barrier, do_mark_object> 4662 ::mark_forwarded_object(oop from_obj, oop to_obj) { 4663 #ifdef ASSERT 4664 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4665 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4666 assert(from_obj != to_obj, "should not be self-forwarded"); 4667 4668 HeapRegion* from_hr = _g1->heap_region_containing(from_obj); 4669 assert(from_hr != NULL, "sanity"); 4670 assert(from_hr->in_collection_set(), "from obj should be in the CSet"); 4671 4672 HeapRegion* to_hr = _g1->heap_region_containing(to_obj); 4673 assert(to_hr != NULL, "sanity"); 4674 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet"); 4675 #endif // ASSERT 4676 4677 // The object might be in the process of being copied by another 4678 // worker so we cannot trust that its to-space image is 4679 // well-formed. So we have to read its size from its from-space 4680 // image which we know should not be changing. 4681 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4682 } 4683 4684 template <G1Barrier barrier, bool do_mark_object> 4685 oop G1ParCopyClosure<barrier, do_mark_object> 4686 ::copy_to_survivor_space(oop old) { 4687 size_t word_sz = old->size(); 4688 HeapRegion* from_region = _g1->heap_region_containing_raw(old); 4689 // +1 to make the -1 indexes valid... 4690 int young_index = from_region->young_index_in_cset()+1; 4691 assert( (from_region->is_young() && young_index > 0) || 4692 (!from_region->is_young() && young_index == 0), "invariant" ); 4693 G1CollectorPolicy* g1p = _g1->g1_policy(); 4694 markOop m = old->mark(); 4695 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4696 : m->age(); 4697 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4698 word_sz); 4699 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz); 4700 #ifndef PRODUCT 4701 // Should this evacuation fail? 4702 if (_g1->evacuation_should_fail()) { 4703 if (obj_ptr != NULL) { 4704 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4705 obj_ptr = NULL; 4706 } 4707 } 4708 #endif // !PRODUCT 4709 4710 if (obj_ptr == NULL) { 4711 // This will either forward-to-self, or detect that someone else has 4712 // installed a forwarding pointer. 4713 return _g1->handle_evacuation_failure_par(_par_scan_state, old); 4714 } 4715 4716 oop obj = oop(obj_ptr); 4717 4718 // We're going to allocate linearly, so might as well prefetch ahead. 4719 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4720 4721 oop forward_ptr = old->forward_to_atomic(obj); 4722 if (forward_ptr == NULL) { 4723 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4724 if (g1p->track_object_age(alloc_purpose)) { 4725 // We could simply do obj->incr_age(). However, this causes a 4726 // performance issue. obj->incr_age() will first check whether 4727 // the object has a displaced mark by checking its mark word; 4728 // getting the mark word from the new location of the object 4729 // stalls. So, given that we already have the mark word and we 4730 // are about to install it anyway, it's better to increase the 4731 // age on the mark word, when the object does not have a 4732 // displaced mark word. We're not expecting many objects to have 4733 // a displaced marked word, so that case is not optimized 4734 // further (it could be...) and we simply call obj->incr_age(). 4735 4736 if (m->has_displaced_mark_helper()) { 4737 // in this case, we have to install the mark word first, 4738 // otherwise obj looks to be forwarded (the old mark word, 4739 // which contains the forward pointer, was copied) 4740 obj->set_mark(m); 4741 obj->incr_age(); 4742 } else { 4743 m = m->incr_age(); 4744 obj->set_mark(m); 4745 } 4746 _par_scan_state->age_table()->add(obj, word_sz); 4747 } else { 4748 obj->set_mark(m); 4749 } 4750 4751 size_t* surv_young_words = _par_scan_state->surviving_young_words(); 4752 surv_young_words[young_index] += word_sz; 4753 4754 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4755 // We keep track of the next start index in the length field of 4756 // the to-space object. The actual length can be found in the 4757 // length field of the from-space object. 4758 arrayOop(obj)->set_length(0); 4759 oop* old_p = set_partial_array_mask(old); 4760 _par_scan_state->push_on_queue(old_p); 4761 } else { 4762 // No point in using the slower heap_region_containing() method, 4763 // given that we know obj is in the heap. 4764 _scanner.set_region(_g1->heap_region_containing_raw(obj)); 4765 obj->oop_iterate_backwards(&_scanner); 4766 } 4767 } else { 4768 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4769 obj = forward_ptr; 4770 } 4771 return obj; 4772 } 4773 4774 template <class T> 4775 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4776 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4777 _scanned_klass->record_modified_oops(); 4778 } 4779 } 4780 4781 template <G1Barrier barrier, bool do_mark_object> 4782 template <class T> 4783 void G1ParCopyClosure<barrier, do_mark_object> 4784 ::do_oop_work(T* p) { 4785 oop obj = oopDesc::load_decode_heap_oop(p); 4786 4787 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4788 4789 // here the null check is implicit in the cset_fast_test() test 4790 if (_g1->in_cset_fast_test(obj)) { 4791 oop forwardee; 4792 if (obj->is_forwarded()) { 4793 forwardee = obj->forwardee(); 4794 } else { 4795 forwardee = copy_to_survivor_space(obj); 4796 } 4797 assert(forwardee != NULL, "forwardee should not be NULL"); 4798 oopDesc::encode_store_heap_oop(p, forwardee); 4799 if (do_mark_object && forwardee != obj) { 4800 // If the object is self-forwarded we don't need to explicitly 4801 // mark it, the evacuation failure protocol will do so. 4802 mark_forwarded_object(obj, forwardee); 4803 } 4804 4805 if (barrier == G1BarrierKlass) { 4806 do_klass_barrier(p, forwardee); 4807 } 4808 } else { 4809 // The object is not in collection set. If we're a root scanning 4810 // closure during an initial mark pause (i.e. do_mark_object will 4811 // be true) then attempt to mark the object. 4812 if (do_mark_object && _g1->is_in_g1_reserved(obj)) { 4813 mark_object(obj); 4814 } 4815 } 4816 4817 if (barrier == G1BarrierEvac && obj != NULL) { 4818 _par_scan_state->update_rs(_from, p, _worker_id); 4819 } 4820 } 4821 4822 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p); 4823 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4824 4825 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) { 4826 assert(has_partial_array_mask(p), "invariant"); 4827 oop from_obj = clear_partial_array_mask(p); 4828 4829 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap."); 4830 assert(from_obj->is_objArray(), "must be obj array"); 4831 objArrayOop from_obj_array = objArrayOop(from_obj); 4832 // The from-space object contains the real length. 4833 int length = from_obj_array->length(); 4834 4835 assert(from_obj->is_forwarded(), "must be forwarded"); 4836 oop to_obj = from_obj->forwardee(); 4837 assert(from_obj != to_obj, "should not be chunking self-forwarded objects"); 4838 objArrayOop to_obj_array = objArrayOop(to_obj); 4839 // We keep track of the next start index in the length field of the 4840 // to-space object. 4841 int next_index = to_obj_array->length(); 4842 assert(0 <= next_index && next_index < length, 4843 err_msg("invariant, next index: %d, length: %d", next_index, length)); 4844 4845 int start = next_index; 4846 int end = length; 4847 int remainder = end - start; 4848 // We'll try not to push a range that's smaller than ParGCArrayScanChunk. 4849 if (remainder > 2 * ParGCArrayScanChunk) { 4850 end = start + ParGCArrayScanChunk; 4851 to_obj_array->set_length(end); 4852 // Push the remainder before we process the range in case another 4853 // worker has run out of things to do and can steal it. 4854 oop* from_obj_p = set_partial_array_mask(from_obj); 4855 _par_scan_state->push_on_queue(from_obj_p); 4856 } else { 4857 assert(length == end, "sanity"); 4858 // We'll process the final range for this object. Restore the length 4859 // so that the heap remains parsable in case of evacuation failure. 4860 to_obj_array->set_length(end); 4861 } 4862 _scanner.set_region(_g1->heap_region_containing_raw(to_obj)); 4863 // Process indexes [start,end). It will also process the header 4864 // along with the first chunk (i.e., the chunk with start == 0). 4865 // Note that at this point the length field of to_obj_array is not 4866 // correct given that we are using it to keep track of the next 4867 // start index. oop_iterate_range() (thankfully!) ignores the length 4868 // field and only relies on the start / end parameters. It does 4869 // however return the size of the object which will be incorrect. So 4870 // we have to ignore it even if we wanted to use it. 4871 to_obj_array->oop_iterate_range(&_scanner, start, end); 4872 } 4873 4874 class G1ParEvacuateFollowersClosure : public VoidClosure { 4875 protected: 4876 G1CollectedHeap* _g1h; 4877 G1ParScanThreadState* _par_scan_state; 4878 RefToScanQueueSet* _queues; 4879 ParallelTaskTerminator* _terminator; 4880 4881 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4882 RefToScanQueueSet* queues() { return _queues; } 4883 ParallelTaskTerminator* terminator() { return _terminator; } 4884 4885 public: 4886 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4887 G1ParScanThreadState* par_scan_state, 4888 RefToScanQueueSet* queues, 4889 ParallelTaskTerminator* terminator) 4890 : _g1h(g1h), _par_scan_state(par_scan_state), 4891 _queues(queues), _terminator(terminator) {} 4892 4893 void do_void(); 4894 4895 private: 4896 inline bool offer_termination(); 4897 }; 4898 4899 bool G1ParEvacuateFollowersClosure::offer_termination() { 4900 G1ParScanThreadState* const pss = par_scan_state(); 4901 pss->start_term_time(); 4902 const bool res = terminator()->offer_termination(); 4903 pss->end_term_time(); 4904 return res; 4905 } 4906 4907 void G1ParEvacuateFollowersClosure::do_void() { 4908 StarTask stolen_task; 4909 G1ParScanThreadState* const pss = par_scan_state(); 4910 pss->trim_queue(); 4911 4912 do { 4913 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4914 assert(pss->verify_task(stolen_task), "sanity"); 4915 if (stolen_task.is_narrow()) { 4916 pss->deal_with_reference((narrowOop*) stolen_task); 4917 } else { 4918 pss->deal_with_reference((oop*) stolen_task); 4919 } 4920 4921 // We've just processed a reference and we might have made 4922 // available new entries on the queues. So we have to make sure 4923 // we drain the queues as necessary. 4924 pss->trim_queue(); 4925 } 4926 } while (!offer_termination()); 4927 4928 pss->retire_alloc_buffers(); 4929 } 4930 4931 class G1KlassScanClosure : public KlassClosure { 4932 G1ParCopyHelper* _closure; 4933 bool _process_only_dirty; 4934 int _count; 4935 public: 4936 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4937 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4938 void do_klass(Klass* klass) { 4939 // If the klass has not been dirtied we know that there's 4940 // no references into the young gen and we can skip it. 4941 if (!_process_only_dirty || klass->has_modified_oops()) { 4942 // Clean the klass since we're going to scavenge all the metadata. 4943 klass->clear_modified_oops(); 4944 4945 // Tell the closure that this klass is the Klass to scavenge 4946 // and is the one to dirty if oops are left pointing into the young gen. 4947 _closure->set_scanned_klass(klass); 4948 4949 klass->oops_do(_closure); 4950 4951 _closure->set_scanned_klass(NULL); 4952 } 4953 _count++; 4954 } 4955 }; 4956 4957 class G1ParTask : public AbstractGangTask { 4958 protected: 4959 G1CollectedHeap* _g1h; 4960 RefToScanQueueSet *_queues; 4961 ParallelTaskTerminator _terminator; 4962 uint _n_workers; 4963 4964 Mutex _stats_lock; 4965 Mutex* stats_lock() { return &_stats_lock; } 4966 4967 size_t getNCards() { 4968 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4969 / G1BlockOffsetSharedArray::N_bytes; 4970 } 4971 4972 public: 4973 G1ParTask(G1CollectedHeap* g1h, 4974 RefToScanQueueSet *task_queues) 4975 : AbstractGangTask("G1 collection"), 4976 _g1h(g1h), 4977 _queues(task_queues), 4978 _terminator(0, _queues), 4979 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4980 {} 4981 4982 RefToScanQueueSet* queues() { return _queues; } 4983 4984 RefToScanQueue *work_queue(int i) { 4985 return queues()->queue(i); 4986 } 4987 4988 ParallelTaskTerminator* terminator() { return &_terminator; } 4989 4990 virtual void set_for_termination(int active_workers) { 4991 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4992 // in the young space (_par_seq_tasks) in the G1 heap 4993 // for SequentialSubTasksDone. 4994 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4995 // both of which need setting by set_n_termination(). 4996 _g1h->SharedHeap::set_n_termination(active_workers); 4997 _g1h->set_n_termination(active_workers); 4998 terminator()->reset_for_reuse(active_workers); 4999 _n_workers = active_workers; 5000 } 5001 5002 void work(uint worker_id) { 5003 if (worker_id >= _n_workers) return; // no work needed this round 5004 5005 double start_time_ms = os::elapsedTime() * 1000.0; 5006 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 5007 5008 { 5009 ResourceMark rm; 5010 HandleMark hm; 5011 5012 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 5013 5014 G1ParScanThreadState pss(_g1h, worker_id); 5015 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp); 5016 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 5017 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp); 5018 5019 pss.set_evac_closure(&scan_evac_cl); 5020 pss.set_evac_failure_closure(&evac_failure_cl); 5021 pss.set_partial_scan_closure(&partial_scan_cl); 5022 5023 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 5024 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 5025 5026 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 5027 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 5028 5029 bool only_young = _g1h->g1_policy()->gcs_are_young(); 5030 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 5031 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 5032 5033 OopClosure* scan_root_cl = &only_scan_root_cl; 5034 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 5035 5036 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5037 // We also need to mark copied objects. 5038 scan_root_cl = &scan_mark_root_cl; 5039 scan_klasses_cl = &scan_mark_klasses_cl_s; 5040 } 5041 5042 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 5043 5044 // Don't scan the scavengable methods in the code cache as part 5045 // of strong root scanning. The code roots that point into a 5046 // region in the collection set are scanned when we scan the 5047 // region's RSet. 5048 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings; 5049 5050 pss.start_strong_roots(); 5051 _g1h->g1_process_strong_roots(/* is scavenging */ true, 5052 SharedHeap::ScanningOption(so), 5053 scan_root_cl, 5054 &push_heap_rs_cl, 5055 scan_klasses_cl, 5056 worker_id); 5057 pss.end_strong_roots(); 5058 5059 { 5060 double start = os::elapsedTime(); 5061 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 5062 evac.do_void(); 5063 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 5064 double term_ms = pss.term_time()*1000.0; 5065 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 5066 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 5067 } 5068 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 5069 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 5070 5071 if (ParallelGCVerbose) { 5072 MutexLocker x(stats_lock()); 5073 pss.print_termination_stats(worker_id); 5074 } 5075 5076 assert(pss.refs()->is_empty(), "should be empty"); 5077 5078 // Close the inner scope so that the ResourceMark and HandleMark 5079 // destructors are executed here and are included as part of the 5080 // "GC Worker Time". 5081 } 5082 5083 double end_time_ms = os::elapsedTime() * 1000.0; 5084 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 5085 } 5086 }; 5087 5088 // *** Common G1 Evacuation Stuff 5089 5090 // This method is run in a GC worker. 5091 5092 void 5093 G1CollectedHeap:: 5094 g1_process_strong_roots(bool is_scavenging, 5095 ScanningOption so, 5096 OopClosure* scan_non_heap_roots, 5097 OopsInHeapRegionClosure* scan_rs, 5098 G1KlassScanClosure* scan_klasses, 5099 int worker_i) { 5100 5101 // First scan the strong roots 5102 double ext_roots_start = os::elapsedTime(); 5103 double closure_app_time_sec = 0.0; 5104 5105 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5106 5107 CodeBlobToOopClosure scan_code_roots(&buf_scan_non_heap_roots, true /* do_marking */); 5108 5109 process_strong_roots(false, // no scoping; this is parallel code 5110 so, 5111 &buf_scan_non_heap_roots, 5112 &scan_code_roots, 5113 scan_klasses 5114 ); 5115 5116 // Now the CM ref_processor roots. 5117 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5118 // We need to treat the discovered reference lists of the 5119 // concurrent mark ref processor as roots and keep entries 5120 // (which are added by the marking threads) on them live 5121 // until they can be processed at the end of marking. 5122 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5123 } 5124 5125 // Finish up any enqueued closure apps (attributed as object copy time). 5126 buf_scan_non_heap_roots.done(); 5127 5128 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 5129 5130 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5131 5132 double ext_root_time_ms = 5133 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5134 5135 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5136 5137 // During conc marking we have to filter the per-thread SATB buffers 5138 // to make sure we remove any oops into the CSet (which will show up 5139 // as implicitly live). 5140 double satb_filtering_ms = 0.0; 5141 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5142 if (mark_in_progress()) { 5143 double satb_filter_start = os::elapsedTime(); 5144 5145 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5146 5147 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5148 } 5149 } 5150 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5151 5152 // If this is an initial mark pause, and we're not scanning 5153 // the entire code cache, we need to mark the oops in the 5154 // strong code root lists for the regions that are not in 5155 // the collection set. 5156 // Note all threads participate in this set of root tasks. 5157 double mark_strong_code_roots_ms = 0.0; 5158 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) { 5159 double mark_strong_roots_start = os::elapsedTime(); 5160 mark_strong_code_roots(worker_i); 5161 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0; 5162 } 5163 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms); 5164 5165 // Now scan the complement of the collection set. 5166 if (scan_rs != NULL) { 5167 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */); 5168 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i); 5169 } 5170 _process_strong_tasks->all_tasks_completed(); 5171 } 5172 5173 void 5174 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) { 5175 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false); 5176 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs); 5177 } 5178 5179 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 5180 private: 5181 BoolObjectClosure* _is_alive; 5182 int _initial_string_table_size; 5183 int _initial_symbol_table_size; 5184 5185 bool _process_strings; 5186 int _strings_processed; 5187 int _strings_removed; 5188 5189 bool _process_symbols; 5190 int _symbols_processed; 5191 int _symbols_removed; 5192 public: 5193 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 5194 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive), 5195 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 5196 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 5197 5198 _initial_string_table_size = StringTable::the_table()->table_size(); 5199 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 5200 if (process_strings) { 5201 StringTable::clear_parallel_claimed_index(); 5202 } 5203 if (process_symbols) { 5204 SymbolTable::clear_parallel_claimed_index(); 5205 } 5206 } 5207 5208 ~G1StringSymbolTableUnlinkTask() { 5209 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 5210 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT, 5211 StringTable::parallel_claimed_index(), _initial_string_table_size)); 5212 guarantee(!_process_strings || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 5213 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT, 5214 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 5215 } 5216 5217 void work(uint worker_id) { 5218 if (G1CollectedHeap::use_parallel_gc_threads()) { 5219 int strings_processed = 0; 5220 int strings_removed = 0; 5221 int symbols_processed = 0; 5222 int symbols_removed = 0; 5223 if (_process_strings) { 5224 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5225 Atomic::add(strings_processed, &_strings_processed); 5226 Atomic::add(strings_removed, &_strings_removed); 5227 } 5228 if (_process_symbols) { 5229 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5230 Atomic::add(symbols_processed, &_symbols_processed); 5231 Atomic::add(symbols_removed, &_symbols_removed); 5232 } 5233 } else { 5234 if (_process_strings) { 5235 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5236 } 5237 if (_process_symbols) { 5238 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5239 } 5240 } 5241 } 5242 5243 size_t strings_processed() const { return (size_t)_strings_processed; } 5244 size_t strings_removed() const { return (size_t)_strings_removed; } 5245 5246 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5247 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5248 }; 5249 5250 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5251 bool process_strings, bool process_symbols) { 5252 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5253 _g1h->workers()->active_workers() : 1); 5254 5255 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5256 if (G1CollectedHeap::use_parallel_gc_threads()) { 5257 set_par_threads(n_workers); 5258 workers()->run_task(&g1_unlink_task); 5259 set_par_threads(0); 5260 } else { 5261 g1_unlink_task.work(0); 5262 } 5263 if (G1TraceStringSymbolTableScrubbing) { 5264 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5265 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5266 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5267 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(), 5268 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed()); 5269 } 5270 } 5271 5272 // Weak Reference Processing support 5273 5274 // An always "is_alive" closure that is used to preserve referents. 5275 // If the object is non-null then it's alive. Used in the preservation 5276 // of referent objects that are pointed to by reference objects 5277 // discovered by the CM ref processor. 5278 class G1AlwaysAliveClosure: public BoolObjectClosure { 5279 G1CollectedHeap* _g1; 5280 public: 5281 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5282 bool do_object_b(oop p) { 5283 if (p != NULL) { 5284 return true; 5285 } 5286 return false; 5287 } 5288 }; 5289 5290 bool G1STWIsAliveClosure::do_object_b(oop p) { 5291 // An object is reachable if it is outside the collection set, 5292 // or is inside and copied. 5293 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5294 } 5295 5296 // Non Copying Keep Alive closure 5297 class G1KeepAliveClosure: public OopClosure { 5298 G1CollectedHeap* _g1; 5299 public: 5300 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5301 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5302 void do_oop( oop* p) { 5303 oop obj = *p; 5304 5305 if (_g1->obj_in_cs(obj)) { 5306 assert( obj->is_forwarded(), "invariant" ); 5307 *p = obj->forwardee(); 5308 } 5309 } 5310 }; 5311 5312 // Copying Keep Alive closure - can be called from both 5313 // serial and parallel code as long as different worker 5314 // threads utilize different G1ParScanThreadState instances 5315 // and different queues. 5316 5317 class G1CopyingKeepAliveClosure: public OopClosure { 5318 G1CollectedHeap* _g1h; 5319 OopClosure* _copy_non_heap_obj_cl; 5320 OopsInHeapRegionClosure* _copy_metadata_obj_cl; 5321 G1ParScanThreadState* _par_scan_state; 5322 5323 public: 5324 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5325 OopClosure* non_heap_obj_cl, 5326 OopsInHeapRegionClosure* metadata_obj_cl, 5327 G1ParScanThreadState* pss): 5328 _g1h(g1h), 5329 _copy_non_heap_obj_cl(non_heap_obj_cl), 5330 _copy_metadata_obj_cl(metadata_obj_cl), 5331 _par_scan_state(pss) 5332 {} 5333 5334 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5335 virtual void do_oop( oop* p) { do_oop_work(p); } 5336 5337 template <class T> void do_oop_work(T* p) { 5338 oop obj = oopDesc::load_decode_heap_oop(p); 5339 5340 if (_g1h->obj_in_cs(obj)) { 5341 // If the referent object has been forwarded (either copied 5342 // to a new location or to itself in the event of an 5343 // evacuation failure) then we need to update the reference 5344 // field and, if both reference and referent are in the G1 5345 // heap, update the RSet for the referent. 5346 // 5347 // If the referent has not been forwarded then we have to keep 5348 // it alive by policy. Therefore we have copy the referent. 5349 // 5350 // If the reference field is in the G1 heap then we can push 5351 // on the PSS queue. When the queue is drained (after each 5352 // phase of reference processing) the object and it's followers 5353 // will be copied, the reference field set to point to the 5354 // new location, and the RSet updated. Otherwise we need to 5355 // use the the non-heap or metadata closures directly to copy 5356 // the referent object and update the pointer, while avoiding 5357 // updating the RSet. 5358 5359 if (_g1h->is_in_g1_reserved(p)) { 5360 _par_scan_state->push_on_queue(p); 5361 } else { 5362 assert(!ClassLoaderDataGraph::contains((address)p), 5363 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) " 5364 PTR_FORMAT, p)); 5365 _copy_non_heap_obj_cl->do_oop(p); 5366 } 5367 } 5368 } 5369 }; 5370 5371 // Serial drain queue closure. Called as the 'complete_gc' 5372 // closure for each discovered list in some of the 5373 // reference processing phases. 5374 5375 class G1STWDrainQueueClosure: public VoidClosure { 5376 protected: 5377 G1CollectedHeap* _g1h; 5378 G1ParScanThreadState* _par_scan_state; 5379 5380 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5381 5382 public: 5383 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5384 _g1h(g1h), 5385 _par_scan_state(pss) 5386 { } 5387 5388 void do_void() { 5389 G1ParScanThreadState* const pss = par_scan_state(); 5390 pss->trim_queue(); 5391 } 5392 }; 5393 5394 // Parallel Reference Processing closures 5395 5396 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5397 // processing during G1 evacuation pauses. 5398 5399 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5400 private: 5401 G1CollectedHeap* _g1h; 5402 RefToScanQueueSet* _queues; 5403 FlexibleWorkGang* _workers; 5404 int _active_workers; 5405 5406 public: 5407 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5408 FlexibleWorkGang* workers, 5409 RefToScanQueueSet *task_queues, 5410 int n_workers) : 5411 _g1h(g1h), 5412 _queues(task_queues), 5413 _workers(workers), 5414 _active_workers(n_workers) 5415 { 5416 assert(n_workers > 0, "shouldn't call this otherwise"); 5417 } 5418 5419 // Executes the given task using concurrent marking worker threads. 5420 virtual void execute(ProcessTask& task); 5421 virtual void execute(EnqueueTask& task); 5422 }; 5423 5424 // Gang task for possibly parallel reference processing 5425 5426 class G1STWRefProcTaskProxy: public AbstractGangTask { 5427 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5428 ProcessTask& _proc_task; 5429 G1CollectedHeap* _g1h; 5430 RefToScanQueueSet *_task_queues; 5431 ParallelTaskTerminator* _terminator; 5432 5433 public: 5434 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5435 G1CollectedHeap* g1h, 5436 RefToScanQueueSet *task_queues, 5437 ParallelTaskTerminator* terminator) : 5438 AbstractGangTask("Process reference objects in parallel"), 5439 _proc_task(proc_task), 5440 _g1h(g1h), 5441 _task_queues(task_queues), 5442 _terminator(terminator) 5443 {} 5444 5445 virtual void work(uint worker_id) { 5446 // The reference processing task executed by a single worker. 5447 ResourceMark rm; 5448 HandleMark hm; 5449 5450 G1STWIsAliveClosure is_alive(_g1h); 5451 5452 G1ParScanThreadState pss(_g1h, worker_id); 5453 5454 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5455 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5456 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5457 5458 pss.set_evac_closure(&scan_evac_cl); 5459 pss.set_evac_failure_closure(&evac_failure_cl); 5460 pss.set_partial_scan_closure(&partial_scan_cl); 5461 5462 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5463 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5464 5465 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5466 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5467 5468 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5469 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_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_metadata_cl = ©_mark_metadata_cl; 5475 } 5476 5477 // Keep alive closure. 5478 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5479 5480 // Complete GC closure 5481 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5482 5483 // Call the reference processing task's work routine. 5484 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5485 5486 // Note we cannot assert that the refs array is empty here as not all 5487 // of the processing tasks (specifically phase2 - pp2_work) execute 5488 // the complete_gc closure (which ordinarily would drain the queue) so 5489 // the queue may not be empty. 5490 } 5491 }; 5492 5493 // Driver routine for parallel reference processing. 5494 // Creates an instance of the ref processing gang 5495 // task and has the worker threads execute it. 5496 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5497 assert(_workers != NULL, "Need parallel worker threads."); 5498 5499 ParallelTaskTerminator terminator(_active_workers, _queues); 5500 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5501 5502 _g1h->set_par_threads(_active_workers); 5503 _workers->run_task(&proc_task_proxy); 5504 _g1h->set_par_threads(0); 5505 } 5506 5507 // Gang task for parallel reference enqueueing. 5508 5509 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5510 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5511 EnqueueTask& _enq_task; 5512 5513 public: 5514 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5515 AbstractGangTask("Enqueue reference objects in parallel"), 5516 _enq_task(enq_task) 5517 { } 5518 5519 virtual void work(uint worker_id) { 5520 _enq_task.work(worker_id); 5521 } 5522 }; 5523 5524 // Driver routine for parallel reference enqueueing. 5525 // Creates an instance of the ref enqueueing gang 5526 // task and has the worker threads execute it. 5527 5528 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5529 assert(_workers != NULL, "Need parallel worker threads."); 5530 5531 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5532 5533 _g1h->set_par_threads(_active_workers); 5534 _workers->run_task(&enq_task_proxy); 5535 _g1h->set_par_threads(0); 5536 } 5537 5538 // End of weak reference support closures 5539 5540 // Abstract task used to preserve (i.e. copy) any referent objects 5541 // that are in the collection set and are pointed to by reference 5542 // objects discovered by the CM ref processor. 5543 5544 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5545 protected: 5546 G1CollectedHeap* _g1h; 5547 RefToScanQueueSet *_queues; 5548 ParallelTaskTerminator _terminator; 5549 uint _n_workers; 5550 5551 public: 5552 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5553 AbstractGangTask("ParPreserveCMReferents"), 5554 _g1h(g1h), 5555 _queues(task_queues), 5556 _terminator(workers, _queues), 5557 _n_workers(workers) 5558 { } 5559 5560 void work(uint worker_id) { 5561 ResourceMark rm; 5562 HandleMark hm; 5563 5564 G1ParScanThreadState pss(_g1h, worker_id); 5565 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5566 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5567 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5568 5569 pss.set_evac_closure(&scan_evac_cl); 5570 pss.set_evac_failure_closure(&evac_failure_cl); 5571 pss.set_partial_scan_closure(&partial_scan_cl); 5572 5573 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5574 5575 5576 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5577 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5578 5579 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5580 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5581 5582 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5583 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5584 5585 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5586 // We also need to mark copied objects. 5587 copy_non_heap_cl = ©_mark_non_heap_cl; 5588 copy_metadata_cl = ©_mark_metadata_cl; 5589 } 5590 5591 // Is alive closure 5592 G1AlwaysAliveClosure always_alive(_g1h); 5593 5594 // Copying keep alive closure. Applied to referent objects that need 5595 // to be copied. 5596 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5597 5598 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5599 5600 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5601 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5602 5603 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5604 // So this must be true - but assert just in case someone decides to 5605 // change the worker ids. 5606 assert(0 <= worker_id && worker_id < limit, "sanity"); 5607 assert(!rp->discovery_is_atomic(), "check this code"); 5608 5609 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5610 for (uint idx = worker_id; idx < limit; idx += stride) { 5611 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5612 5613 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5614 while (iter.has_next()) { 5615 // Since discovery is not atomic for the CM ref processor, we 5616 // can see some null referent objects. 5617 iter.load_ptrs(DEBUG_ONLY(true)); 5618 oop ref = iter.obj(); 5619 5620 // This will filter nulls. 5621 if (iter.is_referent_alive()) { 5622 iter.make_referent_alive(); 5623 } 5624 iter.move_to_next(); 5625 } 5626 } 5627 5628 // Drain the queue - which may cause stealing 5629 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5630 drain_queue.do_void(); 5631 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5632 assert(pss.refs()->is_empty(), "should be"); 5633 } 5634 }; 5635 5636 // Weak Reference processing during an evacuation pause (part 1). 5637 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5638 double ref_proc_start = os::elapsedTime(); 5639 5640 ReferenceProcessor* rp = _ref_processor_stw; 5641 assert(rp->discovery_enabled(), "should have been enabled"); 5642 5643 // Any reference objects, in the collection set, that were 'discovered' 5644 // by the CM ref processor should have already been copied (either by 5645 // applying the external root copy closure to the discovered lists, or 5646 // by following an RSet entry). 5647 // 5648 // But some of the referents, that are in the collection set, that these 5649 // reference objects point to may not have been copied: the STW ref 5650 // processor would have seen that the reference object had already 5651 // been 'discovered' and would have skipped discovering the reference, 5652 // but would not have treated the reference object as a regular oop. 5653 // As a result the copy closure would not have been applied to the 5654 // referent object. 5655 // 5656 // We need to explicitly copy these referent objects - the references 5657 // will be processed at the end of remarking. 5658 // 5659 // We also need to do this copying before we process the reference 5660 // objects discovered by the STW ref processor in case one of these 5661 // referents points to another object which is also referenced by an 5662 // object discovered by the STW ref processor. 5663 5664 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5665 no_of_gc_workers == workers()->active_workers(), 5666 "Need to reset active GC workers"); 5667 5668 set_par_threads(no_of_gc_workers); 5669 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5670 no_of_gc_workers, 5671 _task_queues); 5672 5673 if (G1CollectedHeap::use_parallel_gc_threads()) { 5674 workers()->run_task(&keep_cm_referents); 5675 } else { 5676 keep_cm_referents.work(0); 5677 } 5678 5679 set_par_threads(0); 5680 5681 // Closure to test whether a referent is alive. 5682 G1STWIsAliveClosure is_alive(this); 5683 5684 // Even when parallel reference processing is enabled, the processing 5685 // of JNI refs is serial and performed serially by the current thread 5686 // rather than by a worker. The following PSS will be used for processing 5687 // JNI refs. 5688 5689 // Use only a single queue for this PSS. 5690 G1ParScanThreadState pss(this, 0); 5691 5692 // We do not embed a reference processor in the copying/scanning 5693 // closures while we're actually processing the discovered 5694 // reference objects. 5695 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL); 5696 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5697 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL); 5698 5699 pss.set_evac_closure(&scan_evac_cl); 5700 pss.set_evac_failure_closure(&evac_failure_cl); 5701 pss.set_partial_scan_closure(&partial_scan_cl); 5702 5703 assert(pss.refs()->is_empty(), "pre-condition"); 5704 5705 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5706 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL); 5707 5708 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5709 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL); 5710 5711 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5712 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5713 5714 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5715 // We also need to mark copied objects. 5716 copy_non_heap_cl = ©_mark_non_heap_cl; 5717 copy_metadata_cl = ©_mark_metadata_cl; 5718 } 5719 5720 // Keep alive closure. 5721 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss); 5722 5723 // Serial Complete GC closure 5724 G1STWDrainQueueClosure drain_queue(this, &pss); 5725 5726 // Setup the soft refs policy... 5727 rp->setup_policy(false); 5728 5729 ReferenceProcessorStats stats; 5730 if (!rp->processing_is_mt()) { 5731 // Serial reference processing... 5732 stats = rp->process_discovered_references(&is_alive, 5733 &keep_alive, 5734 &drain_queue, 5735 NULL, 5736 _gc_timer_stw); 5737 } else { 5738 // Parallel reference processing 5739 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5740 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5741 5742 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5743 stats = rp->process_discovered_references(&is_alive, 5744 &keep_alive, 5745 &drain_queue, 5746 &par_task_executor, 5747 _gc_timer_stw); 5748 } 5749 5750 _gc_tracer_stw->report_gc_reference_stats(stats); 5751 // We have completed copying any necessary live referent objects 5752 // (that were not copied during the actual pause) so we can 5753 // retire any active alloc buffers 5754 pss.retire_alloc_buffers(); 5755 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5756 5757 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5758 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5759 } 5760 5761 // Weak Reference processing during an evacuation pause (part 2). 5762 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5763 double ref_enq_start = os::elapsedTime(); 5764 5765 ReferenceProcessor* rp = _ref_processor_stw; 5766 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5767 5768 // Now enqueue any remaining on the discovered lists on to 5769 // the pending list. 5770 if (!rp->processing_is_mt()) { 5771 // Serial reference processing... 5772 rp->enqueue_discovered_references(); 5773 } else { 5774 // Parallel reference enqueueing 5775 5776 assert(no_of_gc_workers == workers()->active_workers(), 5777 "Need to reset active workers"); 5778 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5779 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5780 5781 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5782 rp->enqueue_discovered_references(&par_task_executor); 5783 } 5784 5785 rp->verify_no_references_recorded(); 5786 assert(!rp->discovery_enabled(), "should have been disabled"); 5787 5788 // FIXME 5789 // CM's reference processing also cleans up the string and symbol tables. 5790 // Should we do that here also? We could, but it is a serial operation 5791 // and could significantly increase the pause time. 5792 5793 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5794 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5795 } 5796 5797 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5798 _expand_heap_after_alloc_failure = true; 5799 _evacuation_failed = false; 5800 5801 // Should G1EvacuationFailureALot be in effect for this GC? 5802 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5803 5804 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5805 5806 // Disable the hot card cache. 5807 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5808 hot_card_cache->reset_hot_cache_claimed_index(); 5809 hot_card_cache->set_use_cache(false); 5810 5811 uint n_workers; 5812 if (G1CollectedHeap::use_parallel_gc_threads()) { 5813 n_workers = 5814 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5815 workers()->active_workers(), 5816 Threads::number_of_non_daemon_threads()); 5817 assert(UseDynamicNumberOfGCThreads || 5818 n_workers == workers()->total_workers(), 5819 "If not dynamic should be using all the workers"); 5820 workers()->set_active_workers(n_workers); 5821 set_par_threads(n_workers); 5822 } else { 5823 assert(n_par_threads() == 0, 5824 "Should be the original non-parallel value"); 5825 n_workers = 1; 5826 } 5827 5828 G1ParTask g1_par_task(this, _task_queues); 5829 5830 init_for_evac_failure(NULL); 5831 5832 rem_set()->prepare_for_younger_refs_iterate(true); 5833 5834 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5835 double start_par_time_sec = os::elapsedTime(); 5836 double end_par_time_sec; 5837 5838 { 5839 StrongRootsScope srs(this); 5840 5841 if (G1CollectedHeap::use_parallel_gc_threads()) { 5842 // The individual threads will set their evac-failure closures. 5843 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5844 // These tasks use ShareHeap::_process_strong_tasks 5845 assert(UseDynamicNumberOfGCThreads || 5846 workers()->active_workers() == workers()->total_workers(), 5847 "If not dynamic should be using all the workers"); 5848 workers()->run_task(&g1_par_task); 5849 } else { 5850 g1_par_task.set_for_termination(n_workers); 5851 g1_par_task.work(0); 5852 } 5853 end_par_time_sec = os::elapsedTime(); 5854 5855 // Closing the inner scope will execute the destructor 5856 // for the StrongRootsScope object. We record the current 5857 // elapsed time before closing the scope so that time 5858 // taken for the SRS destructor is NOT included in the 5859 // reported parallel time. 5860 } 5861 5862 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5863 g1_policy()->phase_times()->record_par_time(par_time_ms); 5864 5865 double code_root_fixup_time_ms = 5866 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5867 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5868 5869 set_par_threads(0); 5870 5871 // Process any discovered reference objects - we have 5872 // to do this _before_ we retire the GC alloc regions 5873 // as we may have to copy some 'reachable' referent 5874 // objects (and their reachable sub-graphs) that were 5875 // not copied during the pause. 5876 process_discovered_references(n_workers); 5877 5878 // Weak root processing. 5879 { 5880 G1STWIsAliveClosure is_alive(this); 5881 G1KeepAliveClosure keep_alive(this); 5882 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5883 } 5884 5885 release_gc_alloc_regions(n_workers, evacuation_info); 5886 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5887 5888 // Reset and re-enable the hot card cache. 5889 // Note the counts for the cards in the regions in the 5890 // collection set are reset when the collection set is freed. 5891 hot_card_cache->reset_hot_cache(); 5892 hot_card_cache->set_use_cache(true); 5893 5894 // Migrate the strong code roots attached to each region in 5895 // the collection set. Ideally we would like to do this 5896 // after we have finished the scanning/evacuation of the 5897 // strong code roots for a particular heap region. 5898 migrate_strong_code_roots(); 5899 5900 if (g1_policy()->during_initial_mark_pause()) { 5901 // Reset the claim values set during marking the strong code roots 5902 reset_heap_region_claim_values(); 5903 } 5904 5905 finalize_for_evac_failure(); 5906 5907 if (evacuation_failed()) { 5908 remove_self_forwarding_pointers(); 5909 5910 // Reset the G1EvacuationFailureALot counters and flags 5911 // Note: the values are reset only when an actual 5912 // evacuation failure occurs. 5913 NOT_PRODUCT(reset_evacuation_should_fail();) 5914 } 5915 5916 // Enqueue any remaining references remaining on the STW 5917 // reference processor's discovered lists. We need to do 5918 // this after the card table is cleaned (and verified) as 5919 // the act of enqueueing entries on to the pending list 5920 // will log these updates (and dirty their associated 5921 // cards). We need these updates logged to update any 5922 // RSets. 5923 enqueue_discovered_references(n_workers); 5924 5925 if (G1DeferredRSUpdate) { 5926 RedirtyLoggedCardTableEntryFastClosure redirty; 5927 dirty_card_queue_set().set_closure(&redirty); 5928 dirty_card_queue_set().apply_closure_to_all_completed_buffers(); 5929 5930 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5931 dcq.merge_bufferlists(&dirty_card_queue_set()); 5932 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5933 } 5934 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5935 } 5936 5937 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr, 5938 size_t* pre_used, 5939 FreeRegionList* free_list, 5940 OldRegionSet* old_proxy_set, 5941 HumongousRegionSet* humongous_proxy_set, 5942 HRRSCleanupTask* hrrs_cleanup_task, 5943 bool par) { 5944 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) { 5945 if (hr->isHumongous()) { 5946 assert(hr->startsHumongous(), "we should only see starts humongous"); 5947 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par); 5948 } else { 5949 _old_set.remove_with_proxy(hr, old_proxy_set); 5950 free_region(hr, pre_used, free_list, par); 5951 } 5952 } else { 5953 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task); 5954 } 5955 } 5956 5957 void G1CollectedHeap::free_region(HeapRegion* hr, 5958 size_t* pre_used, 5959 FreeRegionList* free_list, 5960 bool par) { 5961 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5962 assert(!hr->is_empty(), "the region should not be empty"); 5963 assert(free_list != NULL, "pre-condition"); 5964 5965 // Clear the card counts for this region. 5966 // Note: we only need to do this if the region is not young 5967 // (since we don't refine cards in young regions). 5968 if (!hr->is_young()) { 5969 _cg1r->hot_card_cache()->reset_card_counts(hr); 5970 } 5971 *pre_used += hr->used(); 5972 hr->hr_clear(par, true /* clear_space */); 5973 free_list->add_as_head(hr); 5974 } 5975 5976 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5977 size_t* pre_used, 5978 FreeRegionList* free_list, 5979 HumongousRegionSet* humongous_proxy_set, 5980 bool par) { 5981 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5982 assert(free_list != NULL, "pre-condition"); 5983 assert(humongous_proxy_set != NULL, "pre-condition"); 5984 5985 size_t hr_used = hr->used(); 5986 size_t hr_capacity = hr->capacity(); 5987 size_t hr_pre_used = 0; 5988 _humongous_set.remove_with_proxy(hr, humongous_proxy_set); 5989 // We need to read this before we make the region non-humongous, 5990 // otherwise the information will be gone. 5991 uint last_index = hr->last_hc_index(); 5992 hr->set_notHumongous(); 5993 free_region(hr, &hr_pre_used, free_list, par); 5994 5995 uint i = hr->hrs_index() + 1; 5996 while (i < last_index) { 5997 HeapRegion* curr_hr = region_at(i); 5998 assert(curr_hr->continuesHumongous(), "invariant"); 5999 curr_hr->set_notHumongous(); 6000 free_region(curr_hr, &hr_pre_used, free_list, par); 6001 i += 1; 6002 } 6003 assert(hr_pre_used == hr_used, 6004 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" " 6005 "should be the same", hr_pre_used, hr_used)); 6006 *pre_used += hr_pre_used; 6007 } 6008 6009 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used, 6010 FreeRegionList* free_list, 6011 OldRegionSet* old_proxy_set, 6012 HumongousRegionSet* humongous_proxy_set, 6013 bool par) { 6014 if (pre_used > 0) { 6015 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL; 6016 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); 6017 assert(_summary_bytes_used >= pre_used, 6018 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" " 6019 "should be >= pre_used: "SIZE_FORMAT, 6020 _summary_bytes_used, pre_used)); 6021 _summary_bytes_used -= pre_used; 6022 } 6023 if (free_list != NULL && !free_list->is_empty()) { 6024 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6025 _free_list.add_as_head(free_list); 6026 } 6027 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) { 6028 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6029 _old_set.update_from_proxy(old_proxy_set); 6030 } 6031 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) { 6032 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6033 _humongous_set.update_from_proxy(humongous_proxy_set); 6034 } 6035 } 6036 6037 class G1ParCleanupCTTask : public AbstractGangTask { 6038 G1SATBCardTableModRefBS* _ct_bs; 6039 G1CollectedHeap* _g1h; 6040 HeapRegion* volatile _su_head; 6041 public: 6042 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6043 G1CollectedHeap* g1h) : 6044 AbstractGangTask("G1 Par Cleanup CT Task"), 6045 _ct_bs(ct_bs), _g1h(g1h) { } 6046 6047 void work(uint worker_id) { 6048 HeapRegion* r; 6049 while (r = _g1h->pop_dirty_cards_region()) { 6050 clear_cards(r); 6051 } 6052 } 6053 6054 void clear_cards(HeapRegion* r) { 6055 // Cards of the survivors should have already been dirtied. 6056 if (!r->is_survivor()) { 6057 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6058 } 6059 } 6060 }; 6061 6062 #ifndef PRODUCT 6063 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6064 G1CollectedHeap* _g1h; 6065 G1SATBCardTableModRefBS* _ct_bs; 6066 public: 6067 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6068 : _g1h(g1h), _ct_bs(ct_bs) { } 6069 virtual bool doHeapRegion(HeapRegion* r) { 6070 if (r->is_survivor()) { 6071 _g1h->verify_dirty_region(r); 6072 } else { 6073 _g1h->verify_not_dirty_region(r); 6074 } 6075 return false; 6076 } 6077 }; 6078 6079 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6080 // All of the region should be clean. 6081 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6082 MemRegion mr(hr->bottom(), hr->end()); 6083 ct_bs->verify_not_dirty_region(mr); 6084 } 6085 6086 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6087 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6088 // dirty allocated blocks as they allocate them. The thread that 6089 // retires each region and replaces it with a new one will do a 6090 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6091 // not dirty that area (one less thing to have to do while holding 6092 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6093 // is dirty. 6094 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6095 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6096 if (hr->is_young()) { 6097 ct_bs->verify_g1_young_region(mr); 6098 } else { 6099 ct_bs->verify_dirty_region(mr); 6100 } 6101 } 6102 6103 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6104 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6105 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6106 verify_dirty_region(hr); 6107 } 6108 } 6109 6110 void G1CollectedHeap::verify_dirty_young_regions() { 6111 verify_dirty_young_list(_young_list->first_region()); 6112 } 6113 #endif 6114 6115 void G1CollectedHeap::cleanUpCardTable() { 6116 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6117 double start = os::elapsedTime(); 6118 6119 { 6120 // Iterate over the dirty cards region list. 6121 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6122 6123 if (G1CollectedHeap::use_parallel_gc_threads()) { 6124 set_par_threads(); 6125 workers()->run_task(&cleanup_task); 6126 set_par_threads(0); 6127 } else { 6128 while (_dirty_cards_region_list) { 6129 HeapRegion* r = _dirty_cards_region_list; 6130 cleanup_task.clear_cards(r); 6131 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6132 if (_dirty_cards_region_list == r) { 6133 // The last region. 6134 _dirty_cards_region_list = NULL; 6135 } 6136 r->set_next_dirty_cards_region(NULL); 6137 } 6138 } 6139 #ifndef PRODUCT 6140 if (G1VerifyCTCleanup || VerifyAfterGC) { 6141 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6142 heap_region_iterate(&cleanup_verifier); 6143 } 6144 #endif 6145 } 6146 6147 double elapsed = os::elapsedTime() - start; 6148 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6149 } 6150 6151 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6152 size_t pre_used = 0; 6153 FreeRegionList local_free_list("Local List for CSet Freeing"); 6154 6155 double young_time_ms = 0.0; 6156 double non_young_time_ms = 0.0; 6157 6158 // Since the collection set is a superset of the the young list, 6159 // all we need to do to clear the young list is clear its 6160 // head and length, and unlink any young regions in the code below 6161 _young_list->clear(); 6162 6163 G1CollectorPolicy* policy = g1_policy(); 6164 6165 double start_sec = os::elapsedTime(); 6166 bool non_young = true; 6167 6168 HeapRegion* cur = cs_head; 6169 int age_bound = -1; 6170 size_t rs_lengths = 0; 6171 6172 while (cur != NULL) { 6173 assert(!is_on_master_free_list(cur), "sanity"); 6174 if (non_young) { 6175 if (cur->is_young()) { 6176 double end_sec = os::elapsedTime(); 6177 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6178 non_young_time_ms += elapsed_ms; 6179 6180 start_sec = os::elapsedTime(); 6181 non_young = false; 6182 } 6183 } else { 6184 if (!cur->is_young()) { 6185 double end_sec = os::elapsedTime(); 6186 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6187 young_time_ms += elapsed_ms; 6188 6189 start_sec = os::elapsedTime(); 6190 non_young = true; 6191 } 6192 } 6193 6194 rs_lengths += cur->rem_set()->occupied(); 6195 6196 HeapRegion* next = cur->next_in_collection_set(); 6197 assert(cur->in_collection_set(), "bad CS"); 6198 cur->set_next_in_collection_set(NULL); 6199 cur->set_in_collection_set(false); 6200 6201 if (cur->is_young()) { 6202 int index = cur->young_index_in_cset(); 6203 assert(index != -1, "invariant"); 6204 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6205 size_t words_survived = _surviving_young_words[index]; 6206 cur->record_surv_words_in_group(words_survived); 6207 6208 // At this point the we have 'popped' cur from the collection set 6209 // (linked via next_in_collection_set()) but it is still in the 6210 // young list (linked via next_young_region()). Clear the 6211 // _next_young_region field. 6212 cur->set_next_young_region(NULL); 6213 } else { 6214 int index = cur->young_index_in_cset(); 6215 assert(index == -1, "invariant"); 6216 } 6217 6218 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6219 (!cur->is_young() && cur->young_index_in_cset() == -1), 6220 "invariant" ); 6221 6222 if (!cur->evacuation_failed()) { 6223 MemRegion used_mr = cur->used_region(); 6224 6225 // And the region is empty. 6226 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6227 free_region(cur, &pre_used, &local_free_list, false /* par */); 6228 } else { 6229 cur->uninstall_surv_rate_group(); 6230 if (cur->is_young()) { 6231 cur->set_young_index_in_cset(-1); 6232 } 6233 cur->set_not_young(); 6234 cur->set_evacuation_failed(false); 6235 // The region is now considered to be old. 6236 _old_set.add(cur); 6237 evacuation_info.increment_collectionset_used_after(cur->used()); 6238 } 6239 cur = next; 6240 } 6241 6242 evacuation_info.set_regions_freed(local_free_list.length()); 6243 policy->record_max_rs_lengths(rs_lengths); 6244 policy->cset_regions_freed(); 6245 6246 double end_sec = os::elapsedTime(); 6247 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6248 6249 if (non_young) { 6250 non_young_time_ms += elapsed_ms; 6251 } else { 6252 young_time_ms += elapsed_ms; 6253 } 6254 6255 update_sets_after_freeing_regions(pre_used, &local_free_list, 6256 NULL /* old_proxy_set */, 6257 NULL /* humongous_proxy_set */, 6258 false /* par */); 6259 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6260 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6261 } 6262 6263 // This routine is similar to the above but does not record 6264 // any policy statistics or update free lists; we are abandoning 6265 // the current incremental collection set in preparation of a 6266 // full collection. After the full GC we will start to build up 6267 // the incremental collection set again. 6268 // This is only called when we're doing a full collection 6269 // and is immediately followed by the tearing down of the young list. 6270 6271 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6272 HeapRegion* cur = cs_head; 6273 6274 while (cur != NULL) { 6275 HeapRegion* next = cur->next_in_collection_set(); 6276 assert(cur->in_collection_set(), "bad CS"); 6277 cur->set_next_in_collection_set(NULL); 6278 cur->set_in_collection_set(false); 6279 cur->set_young_index_in_cset(-1); 6280 cur = next; 6281 } 6282 } 6283 6284 void G1CollectedHeap::set_free_regions_coming() { 6285 if (G1ConcRegionFreeingVerbose) { 6286 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6287 "setting free regions coming"); 6288 } 6289 6290 assert(!free_regions_coming(), "pre-condition"); 6291 _free_regions_coming = true; 6292 } 6293 6294 void G1CollectedHeap::reset_free_regions_coming() { 6295 assert(free_regions_coming(), "pre-condition"); 6296 6297 { 6298 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6299 _free_regions_coming = false; 6300 SecondaryFreeList_lock->notify_all(); 6301 } 6302 6303 if (G1ConcRegionFreeingVerbose) { 6304 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6305 "reset free regions coming"); 6306 } 6307 } 6308 6309 void G1CollectedHeap::wait_while_free_regions_coming() { 6310 // Most of the time we won't have to wait, so let's do a quick test 6311 // first before we take the lock. 6312 if (!free_regions_coming()) { 6313 return; 6314 } 6315 6316 if (G1ConcRegionFreeingVerbose) { 6317 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6318 "waiting for free regions"); 6319 } 6320 6321 { 6322 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6323 while (free_regions_coming()) { 6324 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6325 } 6326 } 6327 6328 if (G1ConcRegionFreeingVerbose) { 6329 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6330 "done waiting for free regions"); 6331 } 6332 } 6333 6334 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6335 assert(heap_lock_held_for_gc(), 6336 "the heap lock should already be held by or for this thread"); 6337 _young_list->push_region(hr); 6338 } 6339 6340 class NoYoungRegionsClosure: public HeapRegionClosure { 6341 private: 6342 bool _success; 6343 public: 6344 NoYoungRegionsClosure() : _success(true) { } 6345 bool doHeapRegion(HeapRegion* r) { 6346 if (r->is_young()) { 6347 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6348 r->bottom(), r->end()); 6349 _success = false; 6350 } 6351 return false; 6352 } 6353 bool success() { return _success; } 6354 }; 6355 6356 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6357 bool ret = _young_list->check_list_empty(check_sample); 6358 6359 if (check_heap) { 6360 NoYoungRegionsClosure closure; 6361 heap_region_iterate(&closure); 6362 ret = ret && closure.success(); 6363 } 6364 6365 return ret; 6366 } 6367 6368 class TearDownRegionSetsClosure : public HeapRegionClosure { 6369 private: 6370 OldRegionSet *_old_set; 6371 6372 public: 6373 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { } 6374 6375 bool doHeapRegion(HeapRegion* r) { 6376 if (r->is_empty()) { 6377 // We ignore empty regions, we'll empty the free list afterwards 6378 } else if (r->is_young()) { 6379 // We ignore young regions, we'll empty the young list afterwards 6380 } else if (r->isHumongous()) { 6381 // We ignore humongous regions, we're not tearing down the 6382 // humongous region set 6383 } else { 6384 // The rest should be old 6385 _old_set->remove(r); 6386 } 6387 return false; 6388 } 6389 6390 ~TearDownRegionSetsClosure() { 6391 assert(_old_set->is_empty(), "post-condition"); 6392 } 6393 }; 6394 6395 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6396 assert_at_safepoint(true /* should_be_vm_thread */); 6397 6398 if (!free_list_only) { 6399 TearDownRegionSetsClosure cl(&_old_set); 6400 heap_region_iterate(&cl); 6401 6402 // Need to do this after the heap iteration to be able to 6403 // recognize the young regions and ignore them during the iteration. 6404 _young_list->empty_list(); 6405 } 6406 _free_list.remove_all(); 6407 } 6408 6409 class RebuildRegionSetsClosure : public HeapRegionClosure { 6410 private: 6411 bool _free_list_only; 6412 OldRegionSet* _old_set; 6413 FreeRegionList* _free_list; 6414 size_t _total_used; 6415 6416 public: 6417 RebuildRegionSetsClosure(bool free_list_only, 6418 OldRegionSet* old_set, FreeRegionList* free_list) : 6419 _free_list_only(free_list_only), 6420 _old_set(old_set), _free_list(free_list), _total_used(0) { 6421 assert(_free_list->is_empty(), "pre-condition"); 6422 if (!free_list_only) { 6423 assert(_old_set->is_empty(), "pre-condition"); 6424 } 6425 } 6426 6427 bool doHeapRegion(HeapRegion* r) { 6428 if (r->continuesHumongous()) { 6429 return false; 6430 } 6431 6432 if (r->is_empty()) { 6433 // Add free regions to the free list 6434 _free_list->add_as_tail(r); 6435 } else if (!_free_list_only) { 6436 assert(!r->is_young(), "we should not come across young regions"); 6437 6438 if (r->isHumongous()) { 6439 // We ignore humongous regions, we left the humongous set unchanged 6440 } else { 6441 // The rest should be old, add them to the old set 6442 _old_set->add(r); 6443 } 6444 _total_used += r->used(); 6445 } 6446 6447 return false; 6448 } 6449 6450 size_t total_used() { 6451 return _total_used; 6452 } 6453 }; 6454 6455 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6456 assert_at_safepoint(true /* should_be_vm_thread */); 6457 6458 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6459 heap_region_iterate(&cl); 6460 6461 if (!free_list_only) { 6462 _summary_bytes_used = cl.total_used(); 6463 } 6464 assert(_summary_bytes_used == recalculate_used(), 6465 err_msg("inconsistent _summary_bytes_used, " 6466 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6467 _summary_bytes_used, recalculate_used())); 6468 } 6469 6470 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6471 _refine_cte_cl->set_concurrent(concurrent); 6472 } 6473 6474 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6475 HeapRegion* hr = heap_region_containing(p); 6476 if (hr == NULL) { 6477 return false; 6478 } else { 6479 return hr->is_in(p); 6480 } 6481 } 6482 6483 // Methods for the mutator alloc region 6484 6485 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6486 bool force) { 6487 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6488 assert(!force || g1_policy()->can_expand_young_list(), 6489 "if force is true we should be able to expand the young list"); 6490 bool young_list_full = g1_policy()->is_young_list_full(); 6491 if (force || !young_list_full) { 6492 HeapRegion* new_alloc_region = new_region(word_size, 6493 false /* do_expand */); 6494 if (new_alloc_region != NULL) { 6495 set_region_short_lived_locked(new_alloc_region); 6496 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6497 return new_alloc_region; 6498 } 6499 } 6500 return NULL; 6501 } 6502 6503 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6504 size_t allocated_bytes) { 6505 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6506 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6507 6508 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6509 _summary_bytes_used += allocated_bytes; 6510 _hr_printer.retire(alloc_region); 6511 // We update the eden sizes here, when the region is retired, 6512 // instead of when it's allocated, since this is the point that its 6513 // used space has been recored in _summary_bytes_used. 6514 g1mm()->update_eden_size(); 6515 } 6516 6517 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6518 bool force) { 6519 return _g1h->new_mutator_alloc_region(word_size, force); 6520 } 6521 6522 void G1CollectedHeap::set_par_threads() { 6523 // Don't change the number of workers. Use the value previously set 6524 // in the workgroup. 6525 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6526 uint n_workers = workers()->active_workers(); 6527 assert(UseDynamicNumberOfGCThreads || 6528 n_workers == workers()->total_workers(), 6529 "Otherwise should be using the total number of workers"); 6530 if (n_workers == 0) { 6531 assert(false, "Should have been set in prior evacuation pause."); 6532 n_workers = ParallelGCThreads; 6533 workers()->set_active_workers(n_workers); 6534 } 6535 set_par_threads(n_workers); 6536 } 6537 6538 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6539 size_t allocated_bytes) { 6540 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6541 } 6542 6543 // Methods for the GC alloc regions 6544 6545 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6546 uint count, 6547 GCAllocPurpose ap) { 6548 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6549 6550 if (count < g1_policy()->max_regions(ap)) { 6551 HeapRegion* new_alloc_region = new_region(word_size, 6552 true /* do_expand */); 6553 if (new_alloc_region != NULL) { 6554 // We really only need to do this for old regions given that we 6555 // should never scan survivors. But it doesn't hurt to do it 6556 // for survivors too. 6557 new_alloc_region->set_saved_mark(); 6558 if (ap == GCAllocForSurvived) { 6559 new_alloc_region->set_survivor(); 6560 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6561 } else { 6562 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6563 } 6564 bool during_im = g1_policy()->during_initial_mark_pause(); 6565 new_alloc_region->note_start_of_copying(during_im); 6566 return new_alloc_region; 6567 } else { 6568 g1_policy()->note_alloc_region_limit_reached(ap); 6569 } 6570 } 6571 return NULL; 6572 } 6573 6574 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6575 size_t allocated_bytes, 6576 GCAllocPurpose ap) { 6577 bool during_im = g1_policy()->during_initial_mark_pause(); 6578 alloc_region->note_end_of_copying(during_im); 6579 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6580 if (ap == GCAllocForSurvived) { 6581 young_list()->add_survivor_region(alloc_region); 6582 } else { 6583 _old_set.add(alloc_region); 6584 } 6585 _hr_printer.retire(alloc_region); 6586 } 6587 6588 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6589 bool force) { 6590 assert(!force, "not supported for GC alloc regions"); 6591 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6592 } 6593 6594 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6595 size_t allocated_bytes) { 6596 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6597 GCAllocForSurvived); 6598 } 6599 6600 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6601 bool force) { 6602 assert(!force, "not supported for GC alloc regions"); 6603 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6604 } 6605 6606 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6607 size_t allocated_bytes) { 6608 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6609 GCAllocForTenured); 6610 } 6611 // Heap region set verification 6612 6613 class VerifyRegionListsClosure : public HeapRegionClosure { 6614 private: 6615 FreeRegionList* _free_list; 6616 OldRegionSet* _old_set; 6617 HumongousRegionSet* _humongous_set; 6618 uint _region_count; 6619 6620 public: 6621 VerifyRegionListsClosure(OldRegionSet* old_set, 6622 HumongousRegionSet* humongous_set, 6623 FreeRegionList* free_list) : 6624 _old_set(old_set), _humongous_set(humongous_set), 6625 _free_list(free_list), _region_count(0) { } 6626 6627 uint region_count() { return _region_count; } 6628 6629 bool doHeapRegion(HeapRegion* hr) { 6630 _region_count += 1; 6631 6632 if (hr->continuesHumongous()) { 6633 return false; 6634 } 6635 6636 if (hr->is_young()) { 6637 // TODO 6638 } else if (hr->startsHumongous()) { 6639 _humongous_set->verify_next_region(hr); 6640 } else if (hr->is_empty()) { 6641 _free_list->verify_next_region(hr); 6642 } else { 6643 _old_set->verify_next_region(hr); 6644 } 6645 return false; 6646 } 6647 }; 6648 6649 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6650 HeapWord* bottom) { 6651 HeapWord* end = bottom + HeapRegion::GrainWords; 6652 MemRegion mr(bottom, end); 6653 assert(_g1_reserved.contains(mr), "invariant"); 6654 // This might return NULL if the allocation fails 6655 return new HeapRegion(hrs_index, _bot_shared, mr); 6656 } 6657 6658 void G1CollectedHeap::verify_region_sets() { 6659 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6660 6661 // First, check the explicit lists. 6662 _free_list.verify(); 6663 { 6664 // Given that a concurrent operation might be adding regions to 6665 // the secondary free list we have to take the lock before 6666 // verifying it. 6667 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6668 _secondary_free_list.verify(); 6669 } 6670 _old_set.verify(); 6671 _humongous_set.verify(); 6672 6673 // If a concurrent region freeing operation is in progress it will 6674 // be difficult to correctly attributed any free regions we come 6675 // across to the correct free list given that they might belong to 6676 // one of several (free_list, secondary_free_list, any local lists, 6677 // etc.). So, if that's the case we will skip the rest of the 6678 // verification operation. Alternatively, waiting for the concurrent 6679 // operation to complete will have a non-trivial effect on the GC's 6680 // operation (no concurrent operation will last longer than the 6681 // interval between two calls to verification) and it might hide 6682 // any issues that we would like to catch during testing. 6683 if (free_regions_coming()) { 6684 return; 6685 } 6686 6687 // Make sure we append the secondary_free_list on the free_list so 6688 // that all free regions we will come across can be safely 6689 // attributed to the free_list. 6690 append_secondary_free_list_if_not_empty_with_lock(); 6691 6692 // Finally, make sure that the region accounting in the lists is 6693 // consistent with what we see in the heap. 6694 _old_set.verify_start(); 6695 _humongous_set.verify_start(); 6696 _free_list.verify_start(); 6697 6698 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6699 heap_region_iterate(&cl); 6700 6701 _old_set.verify_end(); 6702 _humongous_set.verify_end(); 6703 _free_list.verify_end(); 6704 } 6705 6706 // Optimized nmethod scanning 6707 6708 class RegisterNMethodOopClosure: public OopClosure { 6709 G1CollectedHeap* _g1h; 6710 nmethod* _nm; 6711 6712 template <class T> void do_oop_work(T* p) { 6713 T heap_oop = oopDesc::load_heap_oop(p); 6714 if (!oopDesc::is_null(heap_oop)) { 6715 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6716 HeapRegion* hr = _g1h->heap_region_containing(obj); 6717 assert(!hr->continuesHumongous(), 6718 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6719 " starting at "HR_FORMAT, 6720 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6721 6722 // HeapRegion::add_strong_code_root() avoids adding duplicate 6723 // entries but having duplicates is OK since we "mark" nmethods 6724 // as visited when we scan the strong code root lists during the GC. 6725 hr->add_strong_code_root(_nm); 6726 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 6727 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 6728 _nm, HR_FORMAT_PARAMS(hr))); 6729 } 6730 } 6731 6732 public: 6733 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6734 _g1h(g1h), _nm(nm) {} 6735 6736 void do_oop(oop* p) { do_oop_work(p); } 6737 void do_oop(narrowOop* p) { do_oop_work(p); } 6738 }; 6739 6740 class UnregisterNMethodOopClosure: public OopClosure { 6741 G1CollectedHeap* _g1h; 6742 nmethod* _nm; 6743 6744 template <class T> void do_oop_work(T* p) { 6745 T heap_oop = oopDesc::load_heap_oop(p); 6746 if (!oopDesc::is_null(heap_oop)) { 6747 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6748 HeapRegion* hr = _g1h->heap_region_containing(obj); 6749 assert(!hr->continuesHumongous(), 6750 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6751 " starting at "HR_FORMAT, 6752 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6753 6754 hr->remove_strong_code_root(_nm); 6755 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 6756 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 6757 _nm, HR_FORMAT_PARAMS(hr))); 6758 } 6759 } 6760 6761 public: 6762 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6763 _g1h(g1h), _nm(nm) {} 6764 6765 void do_oop(oop* p) { do_oop_work(p); } 6766 void do_oop(narrowOop* p) { do_oop_work(p); } 6767 }; 6768 6769 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6770 CollectedHeap::register_nmethod(nm); 6771 6772 guarantee(nm != NULL, "sanity"); 6773 RegisterNMethodOopClosure reg_cl(this, nm); 6774 nm->oops_do(®_cl); 6775 } 6776 6777 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6778 CollectedHeap::unregister_nmethod(nm); 6779 6780 guarantee(nm != NULL, "sanity"); 6781 UnregisterNMethodOopClosure reg_cl(this, nm); 6782 nm->oops_do(®_cl, true); 6783 } 6784 6785 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 6786 public: 6787 bool doHeapRegion(HeapRegion *hr) { 6788 assert(!hr->isHumongous(), 6789 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 6790 HR_FORMAT_PARAMS(hr))); 6791 hr->migrate_strong_code_roots(); 6792 return false; 6793 } 6794 }; 6795 6796 void G1CollectedHeap::migrate_strong_code_roots() { 6797 MigrateCodeRootsHeapRegionClosure cl; 6798 double migrate_start = os::elapsedTime(); 6799 collection_set_iterate(&cl); 6800 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 6801 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 6802 } 6803 6804 // Mark all the code roots that point into regions *not* in the 6805 // collection set. 6806 // 6807 // Note we do not want to use a "marking" CodeBlobToOopClosure while 6808 // walking the the code roots lists of regions not in the collection 6809 // set. Suppose we have an nmethod (M) that points to objects in two 6810 // separate regions - one in the collection set (R1) and one not (R2). 6811 // Using a "marking" CodeBlobToOopClosure here would result in "marking" 6812 // nmethod M when walking the code roots for R1. When we come to scan 6813 // the code roots for R2, we would see that M is already marked and it 6814 // would be skipped and the objects in R2 that are referenced from M 6815 // would not be evacuated. 6816 6817 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 6818 6819 class MarkStrongCodeRootOopClosure: public OopClosure { 6820 ConcurrentMark* _cm; 6821 HeapRegion* _hr; 6822 uint _worker_id; 6823 6824 template <class T> void do_oop_work(T* p) { 6825 T heap_oop = oopDesc::load_heap_oop(p); 6826 if (!oopDesc::is_null(heap_oop)) { 6827 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6828 // Only mark objects in the region (which is assumed 6829 // to be not in the collection set). 6830 if (_hr->is_in(obj)) { 6831 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 6832 } 6833 } 6834 } 6835 6836 public: 6837 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) : 6838 _cm(cm), _hr(hr), _worker_id(worker_id) { 6839 assert(!_hr->in_collection_set(), "sanity"); 6840 } 6841 6842 void do_oop(narrowOop* p) { do_oop_work(p); } 6843 void do_oop(oop* p) { do_oop_work(p); } 6844 }; 6845 6846 MarkStrongCodeRootOopClosure _oop_cl; 6847 6848 public: 6849 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id): 6850 _oop_cl(cm, hr, worker_id) {} 6851 6852 void do_code_blob(CodeBlob* cb) { 6853 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 6854 if (nm != NULL) { 6855 nm->oops_do(&_oop_cl); 6856 } 6857 } 6858 }; 6859 6860 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure { 6861 G1CollectedHeap* _g1h; 6862 uint _worker_id; 6863 6864 public: 6865 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) : 6866 _g1h(g1h), _worker_id(worker_id) {} 6867 6868 bool doHeapRegion(HeapRegion *hr) { 6869 HeapRegionRemSet* hrrs = hr->rem_set(); 6870 if (hr->continuesHumongous()) { 6871 // Code roots should never be attached to a continuation of a humongous region 6872 assert(hrrs->strong_code_roots_list_length() == 0, 6873 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT 6874 " starting at "HR_FORMAT", but has "INT32_FORMAT, 6875 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()), 6876 hrrs->strong_code_roots_list_length())); 6877 return false; 6878 } 6879 6880 if (hr->in_collection_set()) { 6881 // Don't mark code roots into regions in the collection set here. 6882 // They will be marked when we scan them. 6883 return false; 6884 } 6885 6886 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id); 6887 hr->strong_code_roots_do(&cb_cl); 6888 return false; 6889 } 6890 }; 6891 6892 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) { 6893 MarkStrongCodeRootsHRClosure cl(this, worker_id); 6894 if (G1CollectedHeap::use_parallel_gc_threads()) { 6895 heap_region_par_iterate_chunked(&cl, 6896 worker_id, 6897 workers()->active_workers(), 6898 HeapRegion::ParMarkRootClaimValue); 6899 } else { 6900 heap_region_iterate(&cl); 6901 } 6902 } 6903 6904 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6905 G1CollectedHeap* _g1h; 6906 6907 public: 6908 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6909 _g1h(g1h) {} 6910 6911 void do_code_blob(CodeBlob* cb) { 6912 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6913 if (nm == NULL) { 6914 return; 6915 } 6916 6917 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) { 6918 _g1h->register_nmethod(nm); 6919 } 6920 } 6921 }; 6922 6923 void G1CollectedHeap::rebuild_strong_code_roots() { 6924 RebuildStrongCodeRootClosure blob_cl(this); 6925 CodeCache::blobs_do(&blob_cl); 6926 }