1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #if !defined(__clang_major__) && defined(__GNUC__) 26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information. 27 #define ATTRIBUTE_PRINTF(x,y) 28 #endif 29 30 #include "precompiled.hpp" 31 #include "classfile/stringTable.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/icBuffer.hpp" 34 #include "gc_implementation/g1/bufferingOopClosure.hpp" 35 #include "gc_implementation/g1/concurrentG1Refine.hpp" 36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 40 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 41 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 42 #include "gc_implementation/g1/g1EvacFailure.hpp" 43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 44 #include "gc_implementation/g1/g1Log.hpp" 45 #include "gc_implementation/g1/g1MarkSweep.hpp" 46 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 47 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 48 #include "gc_implementation/g1/g1RemSet.inline.hpp" 49 #include "gc_implementation/g1/g1StringDedup.hpp" 50 #include "gc_implementation/g1/g1YCTypes.hpp" 51 #include "gc_implementation/g1/heapRegion.inline.hpp" 52 #include "gc_implementation/g1/heapRegionRemSet.hpp" 53 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 54 #include "gc_implementation/g1/vm_operations_g1.hpp" 55 #include "gc_implementation/shared/gcHeapSummary.hpp" 56 #include "gc_implementation/shared/gcTimer.hpp" 57 #include "gc_implementation/shared/gcTrace.hpp" 58 #include "gc_implementation/shared/gcTraceTime.hpp" 59 #include "gc_implementation/shared/isGCActiveMark.hpp" 60 #include "memory/allocation.hpp" 61 #include "memory/gcLocker.inline.hpp" 62 #include "memory/generationSpec.hpp" 63 #include "memory/iterator.hpp" 64 #include "memory/referenceProcessor.hpp" 65 #include "memory/space.inline.hpp" 66 #include "oops/objArrayKlass.hpp" 67 #include "oops/objArrayOop.inline.hpp" 68 #include "oops/oop.inline.hpp" 69 #include "oops/oop.pcgc.inline.hpp" 70 #include "runtime/atomic.inline.hpp" 71 #include "runtime/orderAccess.inline.hpp" 72 #include "runtime/vmThread.hpp" 73 #include "utilities/globalDefinitions.hpp" 74 75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 76 77 // turn it on so that the contents of the young list (scan-only / 78 // to-be-collected) are printed at "strategic" points before / during 79 // / after the collection --- this is useful for debugging 80 #define YOUNG_LIST_VERBOSE 0 81 // CURRENT STATUS 82 // This file is under construction. Search for "FIXME". 83 84 // INVARIANTS/NOTES 85 // 86 // All allocation activity covered by the G1CollectedHeap interface is 87 // serialized by acquiring the HeapLock. This happens in mem_allocate 88 // and allocate_new_tlab, which are the "entry" points to the 89 // allocation code from the rest of the JVM. (Note that this does not 90 // apply to TLAB allocation, which is not part of this interface: it 91 // is done by clients of this interface.) 92 93 // Notes on implementation of parallelism in different tasks. 94 // 95 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 96 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 97 // It does use run_task() which sets _n_workers in the task. 98 // G1ParTask executes g1_process_roots() -> 99 // SharedHeap::process_roots() which calls eventually to 100 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 101 // SequentialSubTasksDone. SharedHeap::process_roots() also 102 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 103 // 104 105 // Local to this file. 106 107 class RefineCardTableEntryClosure: public CardTableEntryClosure { 108 bool _concurrent; 109 public: 110 RefineCardTableEntryClosure() : _concurrent(true) { } 111 112 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 113 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 114 // This path is executed by the concurrent refine or mutator threads, 115 // concurrently, and so we do not care if card_ptr contains references 116 // that point into the collection set. 117 assert(!oops_into_cset, "should be"); 118 119 if (_concurrent && SuspendibleThreadSet::should_yield()) { 120 // Caller will actually yield. 121 return false; 122 } 123 // Otherwise, we finished successfully; return true. 124 return true; 125 } 126 127 void set_concurrent(bool b) { _concurrent = b; } 128 }; 129 130 131 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 132 size_t _num_processed; 133 CardTableModRefBS* _ctbs; 134 int _histo[256]; 135 136 public: 137 ClearLoggedCardTableEntryClosure() : 138 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set()) 139 { 140 for (int i = 0; i < 256; i++) _histo[i] = 0; 141 } 142 143 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 144 unsigned char* ujb = (unsigned char*)card_ptr; 145 int ind = (int)(*ujb); 146 _histo[ind]++; 147 148 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val(); 149 _num_processed++; 150 151 return true; 152 } 153 154 size_t num_processed() { return _num_processed; } 155 156 void print_histo() { 157 gclog_or_tty->print_cr("Card table value histogram:"); 158 for (int i = 0; i < 256; i++) { 159 if (_histo[i] != 0) { 160 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 161 } 162 } 163 } 164 }; 165 166 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 167 private: 168 size_t _num_processed; 169 170 public: 171 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 172 173 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 174 *card_ptr = CardTableModRefBS::dirty_card_val(); 175 _num_processed++; 176 return true; 177 } 178 179 size_t num_processed() const { return _num_processed; } 180 }; 181 182 YoungList::YoungList(G1CollectedHeap* g1h) : 183 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 184 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 185 guarantee(check_list_empty(false), "just making sure..."); 186 } 187 188 void YoungList::push_region(HeapRegion *hr) { 189 assert(!hr->is_young(), "should not already be young"); 190 assert(hr->get_next_young_region() == NULL, "cause it should!"); 191 192 hr->set_next_young_region(_head); 193 _head = hr; 194 195 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 196 ++_length; 197 } 198 199 void YoungList::add_survivor_region(HeapRegion* hr) { 200 assert(hr->is_survivor(), "should be flagged as survivor region"); 201 assert(hr->get_next_young_region() == NULL, "cause it should!"); 202 203 hr->set_next_young_region(_survivor_head); 204 if (_survivor_head == NULL) { 205 _survivor_tail = hr; 206 } 207 _survivor_head = hr; 208 ++_survivor_length; 209 } 210 211 void YoungList::empty_list(HeapRegion* list) { 212 while (list != NULL) { 213 HeapRegion* next = list->get_next_young_region(); 214 list->set_next_young_region(NULL); 215 list->uninstall_surv_rate_group(); 216 list->set_not_young(); 217 list = next; 218 } 219 } 220 221 void YoungList::empty_list() { 222 assert(check_list_well_formed(), "young list should be well formed"); 223 224 empty_list(_head); 225 _head = NULL; 226 _length = 0; 227 228 empty_list(_survivor_head); 229 _survivor_head = NULL; 230 _survivor_tail = NULL; 231 _survivor_length = 0; 232 233 _last_sampled_rs_lengths = 0; 234 235 assert(check_list_empty(false), "just making sure..."); 236 } 237 238 bool YoungList::check_list_well_formed() { 239 bool ret = true; 240 241 uint length = 0; 242 HeapRegion* curr = _head; 243 HeapRegion* last = NULL; 244 while (curr != NULL) { 245 if (!curr->is_young()) { 246 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 247 "incorrectly tagged (y: %d, surv: %d)", 248 curr->bottom(), curr->end(), 249 curr->is_young(), curr->is_survivor()); 250 ret = false; 251 } 252 ++length; 253 last = curr; 254 curr = curr->get_next_young_region(); 255 } 256 ret = ret && (length == _length); 257 258 if (!ret) { 259 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 260 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 261 length, _length); 262 } 263 264 return ret; 265 } 266 267 bool YoungList::check_list_empty(bool check_sample) { 268 bool ret = true; 269 270 if (_length != 0) { 271 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 272 _length); 273 ret = false; 274 } 275 if (check_sample && _last_sampled_rs_lengths != 0) { 276 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 277 ret = false; 278 } 279 if (_head != NULL) { 280 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 281 ret = false; 282 } 283 if (!ret) { 284 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 285 } 286 287 return ret; 288 } 289 290 void 291 YoungList::rs_length_sampling_init() { 292 _sampled_rs_lengths = 0; 293 _curr = _head; 294 } 295 296 bool 297 YoungList::rs_length_sampling_more() { 298 return _curr != NULL; 299 } 300 301 void 302 YoungList::rs_length_sampling_next() { 303 assert( _curr != NULL, "invariant" ); 304 size_t rs_length = _curr->rem_set()->occupied(); 305 306 _sampled_rs_lengths += rs_length; 307 308 // The current region may not yet have been added to the 309 // incremental collection set (it gets added when it is 310 // retired as the current allocation region). 311 if (_curr->in_collection_set()) { 312 // Update the collection set policy information for this region 313 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 314 } 315 316 _curr = _curr->get_next_young_region(); 317 if (_curr == NULL) { 318 _last_sampled_rs_lengths = _sampled_rs_lengths; 319 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 320 } 321 } 322 323 void 324 YoungList::reset_auxilary_lists() { 325 guarantee( is_empty(), "young list should be empty" ); 326 assert(check_list_well_formed(), "young list should be well formed"); 327 328 // Add survivor regions to SurvRateGroup. 329 _g1h->g1_policy()->note_start_adding_survivor_regions(); 330 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 331 332 int young_index_in_cset = 0; 333 for (HeapRegion* curr = _survivor_head; 334 curr != NULL; 335 curr = curr->get_next_young_region()) { 336 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 337 338 // The region is a non-empty survivor so let's add it to 339 // the incremental collection set for the next evacuation 340 // pause. 341 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 342 young_index_in_cset += 1; 343 } 344 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 345 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 346 347 _head = _survivor_head; 348 _length = _survivor_length; 349 if (_survivor_head != NULL) { 350 assert(_survivor_tail != NULL, "cause it shouldn't be"); 351 assert(_survivor_length > 0, "invariant"); 352 _survivor_tail->set_next_young_region(NULL); 353 } 354 355 // Don't clear the survivor list handles until the start of 356 // the next evacuation pause - we need it in order to re-tag 357 // the survivor regions from this evacuation pause as 'young' 358 // at the start of the next. 359 360 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 361 362 assert(check_list_well_formed(), "young list should be well formed"); 363 } 364 365 void YoungList::print() { 366 HeapRegion* lists[] = {_head, _survivor_head}; 367 const char* names[] = {"YOUNG", "SURVIVOR"}; 368 369 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 370 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 371 HeapRegion *curr = lists[list]; 372 if (curr == NULL) 373 gclog_or_tty->print_cr(" empty"); 374 while (curr != NULL) { 375 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 376 HR_FORMAT_PARAMS(curr), 377 curr->prev_top_at_mark_start(), 378 curr->next_top_at_mark_start(), 379 curr->age_in_surv_rate_group_cond()); 380 curr = curr->get_next_young_region(); 381 } 382 } 383 384 gclog_or_tty->cr(); 385 } 386 387 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 388 { 389 // Claim the right to put the region on the dirty cards region list 390 // by installing a self pointer. 391 HeapRegion* next = hr->get_next_dirty_cards_region(); 392 if (next == NULL) { 393 HeapRegion* res = (HeapRegion*) 394 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 395 NULL); 396 if (res == NULL) { 397 HeapRegion* head; 398 do { 399 // Put the region to the dirty cards region list. 400 head = _dirty_cards_region_list; 401 next = (HeapRegion*) 402 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 403 if (next == head) { 404 assert(hr->get_next_dirty_cards_region() == hr, 405 "hr->get_next_dirty_cards_region() != hr"); 406 if (next == NULL) { 407 // The last region in the list points to itself. 408 hr->set_next_dirty_cards_region(hr); 409 } else { 410 hr->set_next_dirty_cards_region(next); 411 } 412 } 413 } while (next != head); 414 } 415 } 416 } 417 418 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 419 { 420 HeapRegion* head; 421 HeapRegion* hr; 422 do { 423 head = _dirty_cards_region_list; 424 if (head == NULL) { 425 return NULL; 426 } 427 HeapRegion* new_head = head->get_next_dirty_cards_region(); 428 if (head == new_head) { 429 // The last region. 430 new_head = NULL; 431 } 432 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 433 head); 434 } while (hr != head); 435 assert(hr != NULL, "invariant"); 436 hr->set_next_dirty_cards_region(NULL); 437 return hr; 438 } 439 440 #ifdef ASSERT 441 // A region is added to the collection set as it is retired 442 // so an address p can point to a region which will be in the 443 // collection set but has not yet been retired. This method 444 // therefore is only accurate during a GC pause after all 445 // regions have been retired. It is used for debugging 446 // to check if an nmethod has references to objects that can 447 // be move during a partial collection. Though it can be 448 // inaccurate, it is sufficient for G1 because the conservative 449 // implementation of is_scavengable() for G1 will indicate that 450 // all nmethods must be scanned during a partial collection. 451 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 452 if (p == NULL) { 453 return false; 454 } 455 return heap_region_containing(p)->in_collection_set(); 456 } 457 #endif 458 459 // Returns true if the reference points to an object that 460 // can move in an incremental collection. 461 bool G1CollectedHeap::is_scavengable(const void* p) { 462 HeapRegion* hr = heap_region_containing(p); 463 return !hr->isHumongous(); 464 } 465 466 void G1CollectedHeap::check_ct_logs_at_safepoint() { 467 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 468 CardTableModRefBS* ct_bs = g1_barrier_set(); 469 470 // Count the dirty cards at the start. 471 CountNonCleanMemRegionClosure count1(this); 472 ct_bs->mod_card_iterate(&count1); 473 int orig_count = count1.n(); 474 475 // First clear the logged cards. 476 ClearLoggedCardTableEntryClosure clear; 477 dcqs.apply_closure_to_all_completed_buffers(&clear); 478 dcqs.iterate_closure_all_threads(&clear, false); 479 clear.print_histo(); 480 481 // Now ensure that there's no dirty cards. 482 CountNonCleanMemRegionClosure count2(this); 483 ct_bs->mod_card_iterate(&count2); 484 if (count2.n() != 0) { 485 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 486 count2.n(), orig_count); 487 } 488 guarantee(count2.n() == 0, "Card table should be clean."); 489 490 RedirtyLoggedCardTableEntryClosure redirty; 491 dcqs.apply_closure_to_all_completed_buffers(&redirty); 492 dcqs.iterate_closure_all_threads(&redirty, false); 493 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 494 clear.num_processed(), orig_count); 495 guarantee(redirty.num_processed() == clear.num_processed(), 496 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT, 497 redirty.num_processed(), clear.num_processed())); 498 499 CountNonCleanMemRegionClosure count3(this); 500 ct_bs->mod_card_iterate(&count3); 501 if (count3.n() != orig_count) { 502 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 503 orig_count, count3.n()); 504 guarantee(count3.n() >= orig_count, "Should have restored them all."); 505 } 506 } 507 508 // Private class members. 509 510 G1CollectedHeap* G1CollectedHeap::_g1h; 511 512 // Private methods. 513 514 HeapRegion* 515 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 516 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 517 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 518 if (!_secondary_free_list.is_empty()) { 519 if (G1ConcRegionFreeingVerbose) { 520 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 521 "secondary_free_list has %u entries", 522 _secondary_free_list.length()); 523 } 524 // It looks as if there are free regions available on the 525 // secondary_free_list. Let's move them to the free_list and try 526 // again to allocate from it. 527 append_secondary_free_list(); 528 529 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 530 "empty we should have moved at least one entry to the free_list"); 531 HeapRegion* res = _free_list.remove_region(is_old); 532 if (G1ConcRegionFreeingVerbose) { 533 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 534 "allocated "HR_FORMAT" from secondary_free_list", 535 HR_FORMAT_PARAMS(res)); 536 } 537 return res; 538 } 539 540 // Wait here until we get notified either when (a) there are no 541 // more free regions coming or (b) some regions have been moved on 542 // the secondary_free_list. 543 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 544 } 545 546 if (G1ConcRegionFreeingVerbose) { 547 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 548 "could not allocate from secondary_free_list"); 549 } 550 return NULL; 551 } 552 553 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 554 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 555 "the only time we use this to allocate a humongous region is " 556 "when we are allocating a single humongous region"); 557 558 HeapRegion* res; 559 if (G1StressConcRegionFreeing) { 560 if (!_secondary_free_list.is_empty()) { 561 if (G1ConcRegionFreeingVerbose) { 562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 563 "forced to look at the secondary_free_list"); 564 } 565 res = new_region_try_secondary_free_list(is_old); 566 if (res != NULL) { 567 return res; 568 } 569 } 570 } 571 572 res = _free_list.remove_region(is_old); 573 574 if (res == NULL) { 575 if (G1ConcRegionFreeingVerbose) { 576 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 577 "res == NULL, trying the secondary_free_list"); 578 } 579 res = new_region_try_secondary_free_list(is_old); 580 } 581 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 582 // Currently, only attempts to allocate GC alloc regions set 583 // do_expand to true. So, we should only reach here during a 584 // safepoint. If this assumption changes we might have to 585 // reconsider the use of _expand_heap_after_alloc_failure. 586 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 587 588 ergo_verbose1(ErgoHeapSizing, 589 "attempt heap expansion", 590 ergo_format_reason("region allocation request failed") 591 ergo_format_byte("allocation request"), 592 word_size * HeapWordSize); 593 if (expand(word_size * HeapWordSize)) { 594 // Given that expand() succeeded in expanding the heap, and we 595 // always expand the heap by an amount aligned to the heap 596 // region size, the free list should in theory not be empty. 597 // In either case remove_region() will check for NULL. 598 res = _free_list.remove_region(is_old); 599 } else { 600 _expand_heap_after_alloc_failure = false; 601 } 602 } 603 return res; 604 } 605 606 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 607 size_t word_size) { 608 assert(isHumongous(word_size), "word_size should be humongous"); 609 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 610 611 uint first = G1_NULL_HRS_INDEX; 612 if (num_regions == 1) { 613 // Only one region to allocate, no need to go through the slower 614 // path. The caller will attempt the expansion if this fails, so 615 // let's not try to expand here too. 616 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 617 if (hr != NULL) { 618 first = hr->hrs_index(); 619 } else { 620 first = G1_NULL_HRS_INDEX; 621 } 622 } else { 623 // We can't allocate humongous regions while cleanupComplete() is 624 // running, since some of the regions we find to be empty might not 625 // yet be added to the free list and it is not straightforward to 626 // know which list they are on so that we can remove them. Note 627 // that we only need to do this if we need to allocate more than 628 // one region to satisfy the current humongous allocation 629 // request. If we are only allocating one region we use the common 630 // region allocation code (see above). 631 wait_while_free_regions_coming(); 632 append_secondary_free_list_if_not_empty_with_lock(); 633 634 if (free_regions() >= num_regions) { 635 first = _hrs.find_contiguous(num_regions); 636 if (first != G1_NULL_HRS_INDEX) { 637 for (uint i = first; i < first + num_regions; ++i) { 638 HeapRegion* hr = region_at(i); 639 assert(hr->is_empty(), "sanity"); 640 assert(is_on_master_free_list(hr), "sanity"); 641 hr->set_pending_removal(true); 642 } 643 _free_list.remove_all_pending(num_regions); 644 } 645 } 646 } 647 return first; 648 } 649 650 HeapWord* 651 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 652 uint num_regions, 653 size_t word_size) { 654 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 655 assert(isHumongous(word_size), "word_size should be humongous"); 656 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 657 658 // Index of last region in the series + 1. 659 uint last = first + num_regions; 660 661 // We need to initialize the region(s) we just discovered. This is 662 // a bit tricky given that it can happen concurrently with 663 // refinement threads refining cards on these regions and 664 // potentially wanting to refine the BOT as they are scanning 665 // those cards (this can happen shortly after a cleanup; see CR 666 // 6991377). So we have to set up the region(s) carefully and in 667 // a specific order. 668 669 // The word size sum of all the regions we will allocate. 670 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 671 assert(word_size <= word_size_sum, "sanity"); 672 673 // This will be the "starts humongous" region. 674 HeapRegion* first_hr = region_at(first); 675 // The header of the new object will be placed at the bottom of 676 // the first region. 677 HeapWord* new_obj = first_hr->bottom(); 678 // This will be the new end of the first region in the series that 679 // should also match the end of the last region in the series. 680 HeapWord* new_end = new_obj + word_size_sum; 681 // This will be the new top of the first region that will reflect 682 // this allocation. 683 HeapWord* new_top = new_obj + word_size; 684 685 // First, we need to zero the header of the space that we will be 686 // allocating. When we update top further down, some refinement 687 // threads might try to scan the region. By zeroing the header we 688 // ensure that any thread that will try to scan the region will 689 // come across the zero klass word and bail out. 690 // 691 // NOTE: It would not have been correct to have used 692 // CollectedHeap::fill_with_object() and make the space look like 693 // an int array. The thread that is doing the allocation will 694 // later update the object header to a potentially different array 695 // type and, for a very short period of time, the klass and length 696 // fields will be inconsistent. This could cause a refinement 697 // thread to calculate the object size incorrectly. 698 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 699 700 // We will set up the first region as "starts humongous". This 701 // will also update the BOT covering all the regions to reflect 702 // that there is a single object that starts at the bottom of the 703 // first region. 704 first_hr->set_startsHumongous(new_top, new_end); 705 706 // Then, if there are any, we will set up the "continues 707 // humongous" regions. 708 HeapRegion* hr = NULL; 709 for (uint i = first + 1; i < last; ++i) { 710 hr = region_at(i); 711 hr->set_continuesHumongous(first_hr); 712 } 713 // If we have "continues humongous" regions (hr != NULL), then the 714 // end of the last one should match new_end. 715 assert(hr == NULL || hr->end() == new_end, "sanity"); 716 717 // Up to this point no concurrent thread would have been able to 718 // do any scanning on any region in this series. All the top 719 // fields still point to bottom, so the intersection between 720 // [bottom,top] and [card_start,card_end] will be empty. Before we 721 // update the top fields, we'll do a storestore to make sure that 722 // no thread sees the update to top before the zeroing of the 723 // object header and the BOT initialization. 724 OrderAccess::storestore(); 725 726 // Now that the BOT and the object header have been initialized, 727 // we can update top of the "starts humongous" region. 728 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 729 "new_top should be in this region"); 730 first_hr->set_top(new_top); 731 if (_hr_printer.is_active()) { 732 HeapWord* bottom = first_hr->bottom(); 733 HeapWord* end = first_hr->orig_end(); 734 if ((first + 1) == last) { 735 // the series has a single humongous region 736 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 737 } else { 738 // the series has more than one humongous regions 739 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 740 } 741 } 742 743 // Now, we will update the top fields of the "continues humongous" 744 // regions. The reason we need to do this is that, otherwise, 745 // these regions would look empty and this will confuse parts of 746 // G1. For example, the code that looks for a consecutive number 747 // of empty regions will consider them empty and try to 748 // re-allocate them. We can extend is_empty() to also include 749 // !continuesHumongous(), but it is easier to just update the top 750 // fields here. The way we set top for all regions (i.e., top == 751 // end for all regions but the last one, top == new_top for the 752 // last one) is actually used when we will free up the humongous 753 // region in free_humongous_region(). 754 hr = NULL; 755 for (uint i = first + 1; i < last; ++i) { 756 hr = region_at(i); 757 if ((i + 1) == last) { 758 // last continues humongous region 759 assert(hr->bottom() < new_top && new_top <= hr->end(), 760 "new_top should fall on this region"); 761 hr->set_top(new_top); 762 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 763 } else { 764 // not last one 765 assert(new_top > hr->end(), "new_top should be above this region"); 766 hr->set_top(hr->end()); 767 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 768 } 769 } 770 // If we have continues humongous regions (hr != NULL), then the 771 // end of the last one should match new_end and its top should 772 // match new_top. 773 assert(hr == NULL || 774 (hr->end() == new_end && hr->top() == new_top), "sanity"); 775 check_bitmaps("Humongous Region Allocation", first_hr); 776 777 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 778 _summary_bytes_used += first_hr->used(); 779 _humongous_set.add(first_hr); 780 781 return new_obj; 782 } 783 784 // If could fit into free regions w/o expansion, try. 785 // Otherwise, if can expand, do so. 786 // Otherwise, if using ex regions might help, try with ex given back. 787 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 788 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 789 790 verify_region_sets_optional(); 791 792 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 793 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 794 uint x_num = expansion_regions(); 795 uint fs = _hrs.free_suffix(); 796 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 797 if (first == G1_NULL_HRS_INDEX) { 798 // The only thing we can do now is attempt expansion. 799 if (fs + x_num >= num_regions) { 800 // If the number of regions we're trying to allocate for this 801 // object is at most the number of regions in the free suffix, 802 // then the call to humongous_obj_allocate_find_first() above 803 // should have succeeded and we wouldn't be here. 804 // 805 // We should only be trying to expand when the free suffix is 806 // not sufficient for the object _and_ we have some expansion 807 // room available. 808 assert(num_regions > fs, "earlier allocation should have succeeded"); 809 810 ergo_verbose1(ErgoHeapSizing, 811 "attempt heap expansion", 812 ergo_format_reason("humongous allocation request failed") 813 ergo_format_byte("allocation request"), 814 word_size * HeapWordSize); 815 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 816 // Even though the heap was expanded, it might not have 817 // reached the desired size. So, we cannot assume that the 818 // allocation will succeed. 819 first = humongous_obj_allocate_find_first(num_regions, word_size); 820 } 821 } 822 } 823 824 HeapWord* result = NULL; 825 if (first != G1_NULL_HRS_INDEX) { 826 result = 827 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 828 assert(result != NULL, "it should always return a valid result"); 829 830 // A successful humongous object allocation changes the used space 831 // information of the old generation so we need to recalculate the 832 // sizes and update the jstat counters here. 833 g1mm()->update_sizes(); 834 } 835 836 verify_region_sets_optional(); 837 838 return result; 839 } 840 841 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 842 assert_heap_not_locked_and_not_at_safepoint(); 843 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 844 845 unsigned int dummy_gc_count_before; 846 int dummy_gclocker_retry_count = 0; 847 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 848 } 849 850 HeapWord* 851 G1CollectedHeap::mem_allocate(size_t word_size, 852 bool* gc_overhead_limit_was_exceeded) { 853 assert_heap_not_locked_and_not_at_safepoint(); 854 855 // Loop until the allocation is satisfied, or unsatisfied after GC. 856 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 857 unsigned int gc_count_before; 858 859 HeapWord* result = NULL; 860 if (!isHumongous(word_size)) { 861 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 862 } else { 863 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 864 } 865 if (result != NULL) { 866 return result; 867 } 868 869 // Create the garbage collection operation... 870 VM_G1CollectForAllocation op(gc_count_before, word_size); 871 // ...and get the VM thread to execute it. 872 VMThread::execute(&op); 873 874 if (op.prologue_succeeded() && op.pause_succeeded()) { 875 // If the operation was successful we'll return the result even 876 // if it is NULL. If the allocation attempt failed immediately 877 // after a Full GC, it's unlikely we'll be able to allocate now. 878 HeapWord* result = op.result(); 879 if (result != NULL && !isHumongous(word_size)) { 880 // Allocations that take place on VM operations do not do any 881 // card dirtying and we have to do it here. We only have to do 882 // this for non-humongous allocations, though. 883 dirty_young_block(result, word_size); 884 } 885 return result; 886 } else { 887 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 888 return NULL; 889 } 890 assert(op.result() == NULL, 891 "the result should be NULL if the VM op did not succeed"); 892 } 893 894 // Give a warning if we seem to be looping forever. 895 if ((QueuedAllocationWarningCount > 0) && 896 (try_count % QueuedAllocationWarningCount == 0)) { 897 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 898 } 899 } 900 901 ShouldNotReachHere(); 902 return NULL; 903 } 904 905 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 906 unsigned int *gc_count_before_ret, 907 int* gclocker_retry_count_ret) { 908 // Make sure you read the note in attempt_allocation_humongous(). 909 910 assert_heap_not_locked_and_not_at_safepoint(); 911 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 912 "be called for humongous allocation requests"); 913 914 // We should only get here after the first-level allocation attempt 915 // (attempt_allocation()) failed to allocate. 916 917 // We will loop until a) we manage to successfully perform the 918 // allocation or b) we successfully schedule a collection which 919 // fails to perform the allocation. b) is the only case when we'll 920 // return NULL. 921 HeapWord* result = NULL; 922 for (int try_count = 1; /* we'll return */; try_count += 1) { 923 bool should_try_gc; 924 unsigned int gc_count_before; 925 926 { 927 MutexLockerEx x(Heap_lock); 928 929 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 930 false /* bot_updates */); 931 if (result != NULL) { 932 return result; 933 } 934 935 // If we reach here, attempt_allocation_locked() above failed to 936 // allocate a new region. So the mutator alloc region should be NULL. 937 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 938 939 if (GC_locker::is_active_and_needs_gc()) { 940 if (g1_policy()->can_expand_young_list()) { 941 // No need for an ergo verbose message here, 942 // can_expand_young_list() does this when it returns true. 943 result = _mutator_alloc_region.attempt_allocation_force(word_size, 944 false /* bot_updates */); 945 if (result != NULL) { 946 return result; 947 } 948 } 949 should_try_gc = false; 950 } else { 951 // The GCLocker may not be active but the GCLocker initiated 952 // GC may not yet have been performed (GCLocker::needs_gc() 953 // returns true). In this case we do not try this GC and 954 // wait until the GCLocker initiated GC is performed, and 955 // then retry the allocation. 956 if (GC_locker::needs_gc()) { 957 should_try_gc = false; 958 } else { 959 // Read the GC count while still holding the Heap_lock. 960 gc_count_before = total_collections(); 961 should_try_gc = true; 962 } 963 } 964 } 965 966 if (should_try_gc) { 967 bool succeeded; 968 result = do_collection_pause(word_size, gc_count_before, &succeeded, 969 GCCause::_g1_inc_collection_pause); 970 if (result != NULL) { 971 assert(succeeded, "only way to get back a non-NULL result"); 972 return result; 973 } 974 975 if (succeeded) { 976 // If we get here we successfully scheduled a collection which 977 // failed to allocate. No point in trying to allocate 978 // further. We'll just return NULL. 979 MutexLockerEx x(Heap_lock); 980 *gc_count_before_ret = total_collections(); 981 return NULL; 982 } 983 } else { 984 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 985 MutexLockerEx x(Heap_lock); 986 *gc_count_before_ret = total_collections(); 987 return NULL; 988 } 989 // The GCLocker is either active or the GCLocker initiated 990 // GC has not yet been performed. Stall until it is and 991 // then retry the allocation. 992 GC_locker::stall_until_clear(); 993 (*gclocker_retry_count_ret) += 1; 994 } 995 996 // We can reach here if we were unsuccessful in scheduling a 997 // collection (because another thread beat us to it) or if we were 998 // stalled due to the GC locker. In either can we should retry the 999 // allocation attempt in case another thread successfully 1000 // performed a collection and reclaimed enough space. We do the 1001 // first attempt (without holding the Heap_lock) here and the 1002 // follow-on attempt will be at the start of the next loop 1003 // iteration (after taking the Heap_lock). 1004 result = _mutator_alloc_region.attempt_allocation(word_size, 1005 false /* bot_updates */); 1006 if (result != NULL) { 1007 return result; 1008 } 1009 1010 // Give a warning if we seem to be looping forever. 1011 if ((QueuedAllocationWarningCount > 0) && 1012 (try_count % QueuedAllocationWarningCount == 0)) { 1013 warning("G1CollectedHeap::attempt_allocation_slow() " 1014 "retries %d times", try_count); 1015 } 1016 } 1017 1018 ShouldNotReachHere(); 1019 return NULL; 1020 } 1021 1022 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1023 unsigned int * gc_count_before_ret, 1024 int* gclocker_retry_count_ret) { 1025 // The structure of this method has a lot of similarities to 1026 // attempt_allocation_slow(). The reason these two were not merged 1027 // into a single one is that such a method would require several "if 1028 // allocation is not humongous do this, otherwise do that" 1029 // conditional paths which would obscure its flow. In fact, an early 1030 // version of this code did use a unified method which was harder to 1031 // follow and, as a result, it had subtle bugs that were hard to 1032 // track down. So keeping these two methods separate allows each to 1033 // be more readable. It will be good to keep these two in sync as 1034 // much as possible. 1035 1036 assert_heap_not_locked_and_not_at_safepoint(); 1037 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1038 "should only be called for humongous allocations"); 1039 1040 // Humongous objects can exhaust the heap quickly, so we should check if we 1041 // need to start a marking cycle at each humongous object allocation. We do 1042 // the check before we do the actual allocation. The reason for doing it 1043 // before the allocation is that we avoid having to keep track of the newly 1044 // allocated memory while we do a GC. 1045 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1046 word_size)) { 1047 collect(GCCause::_g1_humongous_allocation); 1048 } 1049 1050 // We will loop until a) we manage to successfully perform the 1051 // allocation or b) we successfully schedule a collection which 1052 // fails to perform the allocation. b) is the only case when we'll 1053 // return NULL. 1054 HeapWord* result = NULL; 1055 for (int try_count = 1; /* we'll return */; try_count += 1) { 1056 bool should_try_gc; 1057 unsigned int gc_count_before; 1058 1059 { 1060 MutexLockerEx x(Heap_lock); 1061 1062 // Given that humongous objects are not allocated in young 1063 // regions, we'll first try to do the allocation without doing a 1064 // collection hoping that there's enough space in the heap. 1065 result = humongous_obj_allocate(word_size); 1066 if (result != NULL) { 1067 return result; 1068 } 1069 1070 if (GC_locker::is_active_and_needs_gc()) { 1071 should_try_gc = false; 1072 } else { 1073 // The GCLocker may not be active but the GCLocker initiated 1074 // GC may not yet have been performed (GCLocker::needs_gc() 1075 // returns true). In this case we do not try this GC and 1076 // wait until the GCLocker initiated GC is performed, and 1077 // then retry the allocation. 1078 if (GC_locker::needs_gc()) { 1079 should_try_gc = false; 1080 } else { 1081 // Read the GC count while still holding the Heap_lock. 1082 gc_count_before = total_collections(); 1083 should_try_gc = true; 1084 } 1085 } 1086 } 1087 1088 if (should_try_gc) { 1089 // If we failed to allocate the humongous object, we should try to 1090 // do a collection pause (if we're allowed) in case it reclaims 1091 // enough space for the allocation to succeed after the pause. 1092 1093 bool succeeded; 1094 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1095 GCCause::_g1_humongous_allocation); 1096 if (result != NULL) { 1097 assert(succeeded, "only way to get back a non-NULL result"); 1098 return result; 1099 } 1100 1101 if (succeeded) { 1102 // If we get here we successfully scheduled a collection which 1103 // failed to allocate. No point in trying to allocate 1104 // further. We'll just return NULL. 1105 MutexLockerEx x(Heap_lock); 1106 *gc_count_before_ret = total_collections(); 1107 return NULL; 1108 } 1109 } else { 1110 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1111 MutexLockerEx x(Heap_lock); 1112 *gc_count_before_ret = total_collections(); 1113 return NULL; 1114 } 1115 // The GCLocker is either active or the GCLocker initiated 1116 // GC has not yet been performed. Stall until it is and 1117 // then retry the allocation. 1118 GC_locker::stall_until_clear(); 1119 (*gclocker_retry_count_ret) += 1; 1120 } 1121 1122 // We can reach here if we were unsuccessful in scheduling a 1123 // collection (because another thread beat us to it) or if we were 1124 // stalled due to the GC locker. In either can we should retry the 1125 // allocation attempt in case another thread successfully 1126 // performed a collection and reclaimed enough space. Give a 1127 // warning if we seem to be looping forever. 1128 1129 if ((QueuedAllocationWarningCount > 0) && 1130 (try_count % QueuedAllocationWarningCount == 0)) { 1131 warning("G1CollectedHeap::attempt_allocation_humongous() " 1132 "retries %d times", try_count); 1133 } 1134 } 1135 1136 ShouldNotReachHere(); 1137 return NULL; 1138 } 1139 1140 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1141 bool expect_null_mutator_alloc_region) { 1142 assert_at_safepoint(true /* should_be_vm_thread */); 1143 assert(_mutator_alloc_region.get() == NULL || 1144 !expect_null_mutator_alloc_region, 1145 "the current alloc region was unexpectedly found to be non-NULL"); 1146 1147 if (!isHumongous(word_size)) { 1148 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1149 false /* bot_updates */); 1150 } else { 1151 HeapWord* result = humongous_obj_allocate(word_size); 1152 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1153 g1_policy()->set_initiate_conc_mark_if_possible(); 1154 } 1155 return result; 1156 } 1157 1158 ShouldNotReachHere(); 1159 } 1160 1161 class PostMCRemSetClearClosure: public HeapRegionClosure { 1162 G1CollectedHeap* _g1h; 1163 ModRefBarrierSet* _mr_bs; 1164 public: 1165 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1166 _g1h(g1h), _mr_bs(mr_bs) {} 1167 1168 bool doHeapRegion(HeapRegion* r) { 1169 HeapRegionRemSet* hrrs = r->rem_set(); 1170 1171 if (r->continuesHumongous()) { 1172 // We'll assert that the strong code root list and RSet is empty 1173 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1174 assert(hrrs->occupied() == 0, "RSet should be empty"); 1175 return false; 1176 } 1177 1178 _g1h->reset_gc_time_stamps(r); 1179 hrrs->clear(); 1180 // You might think here that we could clear just the cards 1181 // corresponding to the used region. But no: if we leave a dirty card 1182 // in a region we might allocate into, then it would prevent that card 1183 // from being enqueued, and cause it to be missed. 1184 // Re: the performance cost: we shouldn't be doing full GC anyway! 1185 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1186 1187 return false; 1188 } 1189 }; 1190 1191 void G1CollectedHeap::clear_rsets_post_compaction() { 1192 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1193 heap_region_iterate(&rs_clear); 1194 } 1195 1196 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1197 G1CollectedHeap* _g1h; 1198 UpdateRSOopClosure _cl; 1199 int _worker_i; 1200 public: 1201 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1202 _cl(g1->g1_rem_set(), worker_i), 1203 _worker_i(worker_i), 1204 _g1h(g1) 1205 { } 1206 1207 bool doHeapRegion(HeapRegion* r) { 1208 if (!r->continuesHumongous()) { 1209 _cl.set_from(r); 1210 r->oop_iterate(&_cl); 1211 } 1212 return false; 1213 } 1214 }; 1215 1216 class ParRebuildRSTask: public AbstractGangTask { 1217 G1CollectedHeap* _g1; 1218 public: 1219 ParRebuildRSTask(G1CollectedHeap* g1) 1220 : AbstractGangTask("ParRebuildRSTask"), 1221 _g1(g1) 1222 { } 1223 1224 void work(uint worker_id) { 1225 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1226 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1227 _g1->workers()->active_workers(), 1228 HeapRegion::RebuildRSClaimValue); 1229 } 1230 }; 1231 1232 class PostCompactionPrinterClosure: public HeapRegionClosure { 1233 private: 1234 G1HRPrinter* _hr_printer; 1235 public: 1236 bool doHeapRegion(HeapRegion* hr) { 1237 assert(!hr->is_young(), "not expecting to find young regions"); 1238 // We only generate output for non-empty regions. 1239 if (!hr->is_empty()) { 1240 if (!hr->isHumongous()) { 1241 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1242 } else if (hr->startsHumongous()) { 1243 if (hr->region_num() == 1) { 1244 // single humongous region 1245 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1246 } else { 1247 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1248 } 1249 } else { 1250 assert(hr->continuesHumongous(), "only way to get here"); 1251 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1252 } 1253 } 1254 return false; 1255 } 1256 1257 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1258 : _hr_printer(hr_printer) { } 1259 }; 1260 1261 void G1CollectedHeap::print_hrs_post_compaction() { 1262 PostCompactionPrinterClosure cl(hr_printer()); 1263 heap_region_iterate(&cl); 1264 } 1265 1266 bool G1CollectedHeap::do_collection(bool explicit_gc, 1267 bool clear_all_soft_refs, 1268 size_t word_size) { 1269 assert_at_safepoint(true /* should_be_vm_thread */); 1270 1271 if (GC_locker::check_active_before_gc()) { 1272 return false; 1273 } 1274 1275 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1276 gc_timer->register_gc_start(); 1277 1278 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1279 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1280 1281 SvcGCMarker sgcm(SvcGCMarker::FULL); 1282 ResourceMark rm; 1283 1284 print_heap_before_gc(); 1285 trace_heap_before_gc(gc_tracer); 1286 1287 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1288 1289 verify_region_sets_optional(); 1290 1291 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1292 collector_policy()->should_clear_all_soft_refs(); 1293 1294 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1295 1296 { 1297 IsGCActiveMark x; 1298 1299 // Timing 1300 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1301 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1302 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1303 1304 { 1305 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1306 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1307 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1308 1309 double start = os::elapsedTime(); 1310 g1_policy()->record_full_collection_start(); 1311 1312 // Note: When we have a more flexible GC logging framework that 1313 // allows us to add optional attributes to a GC log record we 1314 // could consider timing and reporting how long we wait in the 1315 // following two methods. 1316 wait_while_free_regions_coming(); 1317 // If we start the compaction before the CM threads finish 1318 // scanning the root regions we might trip them over as we'll 1319 // be moving objects / updating references. So let's wait until 1320 // they are done. By telling them to abort, they should complete 1321 // early. 1322 _cm->root_regions()->abort(); 1323 _cm->root_regions()->wait_until_scan_finished(); 1324 append_secondary_free_list_if_not_empty_with_lock(); 1325 1326 gc_prologue(true); 1327 increment_total_collections(true /* full gc */); 1328 increment_old_marking_cycles_started(); 1329 1330 assert(used() == recalculate_used(), "Should be equal"); 1331 1332 verify_before_gc(); 1333 1334 check_bitmaps("Full GC Start"); 1335 pre_full_gc_dump(gc_timer); 1336 1337 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1338 1339 // Disable discovery and empty the discovered lists 1340 // for the CM ref processor. 1341 ref_processor_cm()->disable_discovery(); 1342 ref_processor_cm()->abandon_partial_discovery(); 1343 ref_processor_cm()->verify_no_references_recorded(); 1344 1345 // Abandon current iterations of concurrent marking and concurrent 1346 // refinement, if any are in progress. We have to do this before 1347 // wait_until_scan_finished() below. 1348 concurrent_mark()->abort(); 1349 1350 // Make sure we'll choose a new allocation region afterwards. 1351 release_mutator_alloc_region(); 1352 abandon_gc_alloc_regions(); 1353 g1_rem_set()->cleanupHRRS(); 1354 1355 // We should call this after we retire any currently active alloc 1356 // regions so that all the ALLOC / RETIRE events are generated 1357 // before the start GC event. 1358 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1359 1360 // We may have added regions to the current incremental collection 1361 // set between the last GC or pause and now. We need to clear the 1362 // incremental collection set and then start rebuilding it afresh 1363 // after this full GC. 1364 abandon_collection_set(g1_policy()->inc_cset_head()); 1365 g1_policy()->clear_incremental_cset(); 1366 g1_policy()->stop_incremental_cset_building(); 1367 1368 tear_down_region_sets(false /* free_list_only */); 1369 g1_policy()->set_gcs_are_young(true); 1370 1371 // See the comments in g1CollectedHeap.hpp and 1372 // G1CollectedHeap::ref_processing_init() about 1373 // how reference processing currently works in G1. 1374 1375 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1376 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1377 1378 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1379 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1380 1381 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1382 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1383 1384 // Do collection work 1385 { 1386 HandleMark hm; // Discard invalid handles created during gc 1387 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1388 } 1389 1390 assert(free_regions() == 0, "we should not have added any free regions"); 1391 rebuild_region_sets(false /* free_list_only */); 1392 1393 // Enqueue any discovered reference objects that have 1394 // not been removed from the discovered lists. 1395 ref_processor_stw()->enqueue_discovered_references(); 1396 1397 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1398 1399 MemoryService::track_memory_usage(); 1400 1401 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1402 ref_processor_stw()->verify_no_references_recorded(); 1403 1404 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1405 ClassLoaderDataGraph::purge(); 1406 MetaspaceAux::verify_metrics(); 1407 1408 // Note: since we've just done a full GC, concurrent 1409 // marking is no longer active. Therefore we need not 1410 // re-enable reference discovery for the CM ref processor. 1411 // That will be done at the start of the next marking cycle. 1412 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1413 ref_processor_cm()->verify_no_references_recorded(); 1414 1415 reset_gc_time_stamp(); 1416 // Since everything potentially moved, we will clear all remembered 1417 // sets, and clear all cards. Later we will rebuild remembered 1418 // sets. We will also reset the GC time stamps of the regions. 1419 clear_rsets_post_compaction(); 1420 check_gc_time_stamps(); 1421 1422 // Resize the heap if necessary. 1423 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1424 1425 if (_hr_printer.is_active()) { 1426 // We should do this after we potentially resize the heap so 1427 // that all the COMMIT / UNCOMMIT events are generated before 1428 // the end GC event. 1429 1430 print_hrs_post_compaction(); 1431 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1432 } 1433 1434 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1435 if (hot_card_cache->use_cache()) { 1436 hot_card_cache->reset_card_counts(); 1437 hot_card_cache->reset_hot_cache(); 1438 } 1439 1440 // Rebuild remembered sets of all regions. 1441 if (G1CollectedHeap::use_parallel_gc_threads()) { 1442 uint n_workers = 1443 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1444 workers()->active_workers(), 1445 Threads::number_of_non_daemon_threads()); 1446 assert(UseDynamicNumberOfGCThreads || 1447 n_workers == workers()->total_workers(), 1448 "If not dynamic should be using all the workers"); 1449 workers()->set_active_workers(n_workers); 1450 // Set parallel threads in the heap (_n_par_threads) only 1451 // before a parallel phase and always reset it to 0 after 1452 // the phase so that the number of parallel threads does 1453 // no get carried forward to a serial phase where there 1454 // may be code that is "possibly_parallel". 1455 set_par_threads(n_workers); 1456 1457 ParRebuildRSTask rebuild_rs_task(this); 1458 assert(check_heap_region_claim_values( 1459 HeapRegion::InitialClaimValue), "sanity check"); 1460 assert(UseDynamicNumberOfGCThreads || 1461 workers()->active_workers() == workers()->total_workers(), 1462 "Unless dynamic should use total workers"); 1463 // Use the most recent number of active workers 1464 assert(workers()->active_workers() > 0, 1465 "Active workers not properly set"); 1466 set_par_threads(workers()->active_workers()); 1467 workers()->run_task(&rebuild_rs_task); 1468 set_par_threads(0); 1469 assert(check_heap_region_claim_values( 1470 HeapRegion::RebuildRSClaimValue), "sanity check"); 1471 reset_heap_region_claim_values(); 1472 } else { 1473 RebuildRSOutOfRegionClosure rebuild_rs(this); 1474 heap_region_iterate(&rebuild_rs); 1475 } 1476 1477 // Rebuild the strong code root lists for each region 1478 rebuild_strong_code_roots(); 1479 1480 if (true) { // FIXME 1481 MetaspaceGC::compute_new_size(); 1482 } 1483 1484 #ifdef TRACESPINNING 1485 ParallelTaskTerminator::print_termination_counts(); 1486 #endif 1487 1488 // Discard all rset updates 1489 JavaThread::dirty_card_queue_set().abandon_logs(); 1490 assert(!G1DeferredRSUpdate 1491 || (G1DeferredRSUpdate && 1492 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1493 1494 _young_list->reset_sampled_info(); 1495 // At this point there should be no regions in the 1496 // entire heap tagged as young. 1497 assert(check_young_list_empty(true /* check_heap */), 1498 "young list should be empty at this point"); 1499 1500 // Update the number of full collections that have been completed. 1501 increment_old_marking_cycles_completed(false /* concurrent */); 1502 1503 _hrs.verify_optional(); 1504 verify_region_sets_optional(); 1505 1506 verify_after_gc(); 1507 1508 // Clear the previous marking bitmap, if needed for bitmap verification. 1509 // Note we cannot do this when we clear the next marking bitmap in 1510 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1511 // objects marked during a full GC against the previous bitmap. 1512 // But we need to clear it before calling check_bitmaps below since 1513 // the full GC has compacted objects and updated TAMS but not updated 1514 // the prev bitmap. 1515 if (G1VerifyBitmaps) { 1516 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1517 } 1518 check_bitmaps("Full GC End"); 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_cset_fast_test(); 1525 1526 init_mutator_alloc_region(); 1527 1528 double end = os::elapsedTime(); 1529 g1_policy()->record_full_collection_end(); 1530 1531 if (G1Log::fine()) { 1532 g1_policy()->print_heap_transition(); 1533 } 1534 1535 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1536 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1537 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1538 // before any GC notifications are raised. 1539 g1mm()->update_sizes(); 1540 1541 gc_epilogue(true); 1542 } 1543 1544 if (G1Log::finer()) { 1545 g1_policy()->print_detailed_heap_transition(true /* full */); 1546 } 1547 1548 print_heap_after_gc(); 1549 trace_heap_after_gc(gc_tracer); 1550 1551 post_full_gc_dump(gc_timer); 1552 1553 gc_timer->register_gc_end(); 1554 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1555 } 1556 1557 return true; 1558 } 1559 1560 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1561 // do_collection() will return whether it succeeded in performing 1562 // the GC. Currently, there is no facility on the 1563 // do_full_collection() API to notify the caller than the collection 1564 // did not succeed (e.g., because it was locked out by the GC 1565 // locker). So, right now, we'll ignore the return value. 1566 bool dummy = do_collection(true, /* explicit_gc */ 1567 clear_all_soft_refs, 1568 0 /* word_size */); 1569 } 1570 1571 // This code is mostly copied from TenuredGeneration. 1572 void 1573 G1CollectedHeap:: 1574 resize_if_necessary_after_full_collection(size_t word_size) { 1575 // Include the current allocation, if any, and bytes that will be 1576 // pre-allocated to support collections, as "used". 1577 const size_t used_after_gc = used(); 1578 const size_t capacity_after_gc = capacity(); 1579 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1580 1581 // This is enforced in arguments.cpp. 1582 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1583 "otherwise the code below doesn't make sense"); 1584 1585 // We don't have floating point command-line arguments 1586 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1587 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1588 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1589 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1590 1591 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1592 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1593 1594 // We have to be careful here as these two calculations can overflow 1595 // 32-bit size_t's. 1596 double used_after_gc_d = (double) used_after_gc; 1597 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1598 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1599 1600 // Let's make sure that they are both under the max heap size, which 1601 // by default will make them fit into a size_t. 1602 double desired_capacity_upper_bound = (double) max_heap_size; 1603 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1604 desired_capacity_upper_bound); 1605 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1606 desired_capacity_upper_bound); 1607 1608 // We can now safely turn them into size_t's. 1609 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1610 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1611 1612 // This assert only makes sense here, before we adjust them 1613 // with respect to the min and max heap size. 1614 assert(minimum_desired_capacity <= maximum_desired_capacity, 1615 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1616 "maximum_desired_capacity = "SIZE_FORMAT, 1617 minimum_desired_capacity, maximum_desired_capacity)); 1618 1619 // Should not be greater than the heap max size. No need to adjust 1620 // it with respect to the heap min size as it's a lower bound (i.e., 1621 // we'll try to make the capacity larger than it, not smaller). 1622 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1623 // Should not be less than the heap min size. No need to adjust it 1624 // with respect to the heap max size as it's an upper bound (i.e., 1625 // we'll try to make the capacity smaller than it, not greater). 1626 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1627 1628 if (capacity_after_gc < minimum_desired_capacity) { 1629 // Don't expand unless it's significant 1630 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1631 ergo_verbose4(ErgoHeapSizing, 1632 "attempt heap expansion", 1633 ergo_format_reason("capacity lower than " 1634 "min desired capacity after Full GC") 1635 ergo_format_byte("capacity") 1636 ergo_format_byte("occupancy") 1637 ergo_format_byte_perc("min desired capacity"), 1638 capacity_after_gc, used_after_gc, 1639 minimum_desired_capacity, (double) MinHeapFreeRatio); 1640 expand(expand_bytes); 1641 1642 // No expansion, now see if we want to shrink 1643 } else if (capacity_after_gc > maximum_desired_capacity) { 1644 // Capacity too large, compute shrinking size 1645 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1646 ergo_verbose4(ErgoHeapSizing, 1647 "attempt heap shrinking", 1648 ergo_format_reason("capacity higher than " 1649 "max desired capacity after Full GC") 1650 ergo_format_byte("capacity") 1651 ergo_format_byte("occupancy") 1652 ergo_format_byte_perc("max desired capacity"), 1653 capacity_after_gc, used_after_gc, 1654 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1655 shrink(shrink_bytes); 1656 } 1657 } 1658 1659 1660 HeapWord* 1661 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1662 bool* succeeded) { 1663 assert_at_safepoint(true /* should_be_vm_thread */); 1664 1665 *succeeded = true; 1666 // Let's attempt the allocation first. 1667 HeapWord* result = 1668 attempt_allocation_at_safepoint(word_size, 1669 false /* expect_null_mutator_alloc_region */); 1670 if (result != NULL) { 1671 assert(*succeeded, "sanity"); 1672 return result; 1673 } 1674 1675 // In a G1 heap, we're supposed to keep allocation from failing by 1676 // incremental pauses. Therefore, at least for now, we'll favor 1677 // expansion over collection. (This might change in the future if we can 1678 // do something smarter than full collection to satisfy a failed alloc.) 1679 result = expand_and_allocate(word_size); 1680 if (result != NULL) { 1681 assert(*succeeded, "sanity"); 1682 return result; 1683 } 1684 1685 // Expansion didn't work, we'll try to do a Full GC. 1686 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1687 false, /* clear_all_soft_refs */ 1688 word_size); 1689 if (!gc_succeeded) { 1690 *succeeded = false; 1691 return NULL; 1692 } 1693 1694 // Retry the allocation 1695 result = attempt_allocation_at_safepoint(word_size, 1696 true /* expect_null_mutator_alloc_region */); 1697 if (result != NULL) { 1698 assert(*succeeded, "sanity"); 1699 return result; 1700 } 1701 1702 // Then, try a Full GC that will collect all soft references. 1703 gc_succeeded = do_collection(false, /* explicit_gc */ 1704 true, /* clear_all_soft_refs */ 1705 word_size); 1706 if (!gc_succeeded) { 1707 *succeeded = false; 1708 return NULL; 1709 } 1710 1711 // Retry the allocation once more 1712 result = attempt_allocation_at_safepoint(word_size, 1713 true /* expect_null_mutator_alloc_region */); 1714 if (result != NULL) { 1715 assert(*succeeded, "sanity"); 1716 return result; 1717 } 1718 1719 assert(!collector_policy()->should_clear_all_soft_refs(), 1720 "Flag should have been handled and cleared prior to this point"); 1721 1722 // What else? We might try synchronous finalization later. If the total 1723 // space available is large enough for the allocation, then a more 1724 // complete compaction phase than we've tried so far might be 1725 // appropriate. 1726 assert(*succeeded, "sanity"); 1727 return NULL; 1728 } 1729 1730 // Attempting to expand the heap sufficiently 1731 // to support an allocation of the given "word_size". If 1732 // successful, perform the allocation and return the address of the 1733 // allocated block, or else "NULL". 1734 1735 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1736 assert_at_safepoint(true /* should_be_vm_thread */); 1737 1738 verify_region_sets_optional(); 1739 1740 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1741 ergo_verbose1(ErgoHeapSizing, 1742 "attempt heap expansion", 1743 ergo_format_reason("allocation request failed") 1744 ergo_format_byte("allocation request"), 1745 word_size * HeapWordSize); 1746 if (expand(expand_bytes)) { 1747 _hrs.verify_optional(); 1748 verify_region_sets_optional(); 1749 return attempt_allocation_at_safepoint(word_size, 1750 false /* expect_null_mutator_alloc_region */); 1751 } 1752 return NULL; 1753 } 1754 1755 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1756 HeapWord* new_end) { 1757 assert(old_end != new_end, "don't call this otherwise"); 1758 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1759 1760 // Update the committed mem region. 1761 _g1_committed.set_end(new_end); 1762 // Tell the card table about the update. 1763 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1764 // Tell the BOT about the update. 1765 _bot_shared->resize(_g1_committed.word_size()); 1766 // Tell the hot card cache about the update 1767 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1768 } 1769 1770 bool G1CollectedHeap::expand(size_t expand_bytes) { 1771 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1772 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1773 HeapRegion::GrainBytes); 1774 ergo_verbose2(ErgoHeapSizing, 1775 "expand the heap", 1776 ergo_format_byte("requested expansion amount") 1777 ergo_format_byte("attempted expansion amount"), 1778 expand_bytes, aligned_expand_bytes); 1779 1780 if (_g1_storage.uncommitted_size() == 0) { 1781 ergo_verbose0(ErgoHeapSizing, 1782 "did not expand the heap", 1783 ergo_format_reason("heap already fully expanded")); 1784 return false; 1785 } 1786 1787 // First commit the memory. 1788 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1789 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1790 if (successful) { 1791 // Then propagate this update to the necessary data structures. 1792 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1793 update_committed_space(old_end, new_end); 1794 1795 FreeRegionList expansion_list("Local Expansion List"); 1796 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1797 assert(mr.start() == old_end, "post-condition"); 1798 // mr might be a smaller region than what was requested if 1799 // expand_by() was unable to allocate the HeapRegion instances 1800 assert(mr.end() <= new_end, "post-condition"); 1801 1802 size_t actual_expand_bytes = mr.byte_size(); 1803 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1804 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1805 "post-condition"); 1806 if (actual_expand_bytes < aligned_expand_bytes) { 1807 // We could not expand _hrs to the desired size. In this case we 1808 // need to shrink the committed space accordingly. 1809 assert(mr.end() < new_end, "invariant"); 1810 1811 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1812 // First uncommit the memory. 1813 _g1_storage.shrink_by(diff_bytes); 1814 // Then propagate this update to the necessary data structures. 1815 update_committed_space(new_end, mr.end()); 1816 } 1817 _free_list.add_as_tail(&expansion_list); 1818 1819 if (_hr_printer.is_active()) { 1820 HeapWord* curr = mr.start(); 1821 while (curr < mr.end()) { 1822 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1823 _hr_printer.commit(curr, curr_end); 1824 curr = curr_end; 1825 } 1826 assert(curr == mr.end(), "post-condition"); 1827 } 1828 g1_policy()->record_new_heap_size(n_regions()); 1829 } else { 1830 ergo_verbose0(ErgoHeapSizing, 1831 "did not expand the heap", 1832 ergo_format_reason("heap expansion operation failed")); 1833 // The expansion of the virtual storage space was unsuccessful. 1834 // Let's see if it was because we ran out of swap. 1835 if (G1ExitOnExpansionFailure && 1836 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1837 // We had head room... 1838 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1839 } 1840 } 1841 return successful; 1842 } 1843 1844 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1845 size_t aligned_shrink_bytes = 1846 ReservedSpace::page_align_size_down(shrink_bytes); 1847 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1848 HeapRegion::GrainBytes); 1849 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1850 1851 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1852 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1853 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1854 1855 ergo_verbose3(ErgoHeapSizing, 1856 "shrink the heap", 1857 ergo_format_byte("requested shrinking amount") 1858 ergo_format_byte("aligned shrinking amount") 1859 ergo_format_byte("attempted shrinking amount"), 1860 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1861 if (num_regions_removed > 0) { 1862 _g1_storage.shrink_by(shrunk_bytes); 1863 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1864 1865 if (_hr_printer.is_active()) { 1866 HeapWord* curr = old_end; 1867 while (curr > new_end) { 1868 HeapWord* curr_end = curr; 1869 curr -= HeapRegion::GrainWords; 1870 _hr_printer.uncommit(curr, curr_end); 1871 } 1872 } 1873 1874 _expansion_regions += num_regions_removed; 1875 update_committed_space(old_end, new_end); 1876 HeapRegionRemSet::shrink_heap(n_regions()); 1877 g1_policy()->record_new_heap_size(n_regions()); 1878 } else { 1879 ergo_verbose0(ErgoHeapSizing, 1880 "did not shrink the heap", 1881 ergo_format_reason("heap shrinking operation failed")); 1882 } 1883 } 1884 1885 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1886 verify_region_sets_optional(); 1887 1888 // We should only reach here at the end of a Full GC which means we 1889 // should not not be holding to any GC alloc regions. The method 1890 // below will make sure of that and do any remaining clean up. 1891 abandon_gc_alloc_regions(); 1892 1893 // Instead of tearing down / rebuilding the free lists here, we 1894 // could instead use the remove_all_pending() method on free_list to 1895 // remove only the ones that we need to remove. 1896 tear_down_region_sets(true /* free_list_only */); 1897 shrink_helper(shrink_bytes); 1898 rebuild_region_sets(true /* free_list_only */); 1899 1900 _hrs.verify_optional(); 1901 verify_region_sets_optional(); 1902 } 1903 1904 // Public methods. 1905 1906 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1907 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1908 #endif // _MSC_VER 1909 1910 1911 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1912 SharedHeap(policy_), 1913 _g1_policy(policy_), 1914 _dirty_card_queue_set(false), 1915 _into_cset_dirty_card_queue_set(false), 1916 _is_alive_closure_cm(this), 1917 _is_alive_closure_stw(this), 1918 _ref_processor_cm(NULL), 1919 _ref_processor_stw(NULL), 1920 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1921 _bot_shared(NULL), 1922 _evac_failure_scan_stack(NULL), 1923 _mark_in_progress(false), 1924 _cg1r(NULL), _summary_bytes_used(0), 1925 _g1mm(NULL), 1926 _refine_cte_cl(NULL), 1927 _full_collection(false), 1928 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()), 1929 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1930 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1931 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1932 _humongous_is_live(), 1933 _has_humongous_reclaim_candidates(false), 1934 _free_regions_coming(false), 1935 _young_list(new YoungList(this)), 1936 _gc_time_stamp(0), 1937 _retained_old_gc_alloc_region(NULL), 1938 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1939 _old_plab_stats(OldPLABSize, PLABWeight), 1940 _expand_heap_after_alloc_failure(true), 1941 _surviving_young_words(NULL), 1942 _old_marking_cycles_started(0), 1943 _old_marking_cycles_completed(0), 1944 _concurrent_cycle_started(false), 1945 _in_cset_fast_test(), 1946 _dirty_cards_region_list(NULL), 1947 _worker_cset_start_region(NULL), 1948 _worker_cset_start_region_time_stamp(NULL), 1949 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1950 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1951 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1952 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1953 1954 _g1h = this; 1955 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1956 vm_exit_during_initialization("Failed necessary allocation."); 1957 } 1958 1959 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1960 1961 int n_queues = MAX2((int)ParallelGCThreads, 1); 1962 _task_queues = new RefToScanQueueSet(n_queues); 1963 1964 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1965 assert(n_rem_sets > 0, "Invariant."); 1966 1967 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1968 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1969 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1970 1971 for (int i = 0; i < n_queues; i++) { 1972 RefToScanQueue* q = new RefToScanQueue(); 1973 q->initialize(); 1974 _task_queues->register_queue(i, q); 1975 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1976 } 1977 clear_cset_start_regions(); 1978 1979 // Initialize the G1EvacuationFailureALot counters and flags. 1980 NOT_PRODUCT(reset_evacuation_should_fail();) 1981 1982 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1983 } 1984 1985 jint G1CollectedHeap::initialize() { 1986 CollectedHeap::pre_initialize(); 1987 os::enable_vtime(); 1988 1989 G1Log::init(); 1990 1991 // Necessary to satisfy locking discipline assertions. 1992 1993 MutexLocker x(Heap_lock); 1994 1995 // We have to initialize the printer before committing the heap, as 1996 // it will be used then. 1997 _hr_printer.set_active(G1PrintHeapRegions); 1998 1999 // While there are no constraints in the GC code that HeapWordSize 2000 // be any particular value, there are multiple other areas in the 2001 // system which believe this to be true (e.g. oop->object_size in some 2002 // cases incorrectly returns the size in wordSize units rather than 2003 // HeapWordSize). 2004 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2005 2006 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2007 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2008 size_t heap_alignment = collector_policy()->heap_alignment(); 2009 2010 // Ensure that the sizes are properly aligned. 2011 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2012 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2013 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2014 2015 _refine_cte_cl = new RefineCardTableEntryClosure(); 2016 2017 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 2018 2019 // Reserve the maximum. 2020 2021 // When compressed oops are enabled, the preferred heap base 2022 // is calculated by subtracting the requested size from the 2023 // 32Gb boundary and using the result as the base address for 2024 // heap reservation. If the requested size is not aligned to 2025 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2026 // into the ReservedHeapSpace constructor) then the actual 2027 // base of the reserved heap may end up differing from the 2028 // address that was requested (i.e. the preferred heap base). 2029 // If this happens then we could end up using a non-optimal 2030 // compressed oops mode. 2031 2032 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2033 heap_alignment); 2034 2035 // It is important to do this in a way such that concurrent readers can't 2036 // temporarily think something is in the heap. (I've actually seen this 2037 // happen in asserts: DLD.) 2038 _reserved.set_word_size(0); 2039 _reserved.set_start((HeapWord*)heap_rs.base()); 2040 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2041 2042 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2043 2044 // Create the gen rem set (and barrier set) for the entire reserved region. 2045 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2046 set_barrier_set(rem_set()->bs()); 2047 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2048 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2049 return JNI_ENOMEM; 2050 } 2051 2052 // Also create a G1 rem set. 2053 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2054 2055 // Carve out the G1 part of the heap. 2056 2057 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2058 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2059 g1_rs.size()/HeapWordSize); 2060 2061 _g1_storage.initialize(g1_rs, 0); 2062 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2063 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2064 (HeapWord*) _g1_reserved.end()); 2065 assert(_hrs.max_length() == _expansion_regions, 2066 err_msg("max length: %u expansion regions: %u", 2067 _hrs.max_length(), _expansion_regions)); 2068 2069 // Do later initialization work for concurrent refinement. 2070 _cg1r->init(); 2071 2072 // 6843694 - ensure that the maximum region index can fit 2073 // in the remembered set structures. 2074 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2075 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2076 2077 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2078 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2079 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2080 "too many cards per region"); 2081 2082 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2083 2084 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2085 heap_word_size(init_byte_size)); 2086 2087 _g1h = this; 2088 2089 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes); 2090 _humongous_is_live.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes); 2091 2092 // Create the ConcurrentMark data structure and thread. 2093 // (Must do this late, so that "max_regions" is defined.) 2094 _cm = new ConcurrentMark(this, heap_rs); 2095 if (_cm == NULL || !_cm->completed_initialization()) { 2096 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2097 return JNI_ENOMEM; 2098 } 2099 _cmThread = _cm->cmThread(); 2100 2101 // Initialize the from_card cache structure of HeapRegionRemSet. 2102 HeapRegionRemSet::init_heap(max_regions()); 2103 2104 // Now expand into the initial heap size. 2105 if (!expand(init_byte_size)) { 2106 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2107 return JNI_ENOMEM; 2108 } 2109 2110 // Perform any initialization actions delegated to the policy. 2111 g1_policy()->init(); 2112 2113 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2114 SATB_Q_FL_lock, 2115 G1SATBProcessCompletedThreshold, 2116 Shared_SATB_Q_lock); 2117 2118 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2119 DirtyCardQ_CBL_mon, 2120 DirtyCardQ_FL_lock, 2121 concurrent_g1_refine()->yellow_zone(), 2122 concurrent_g1_refine()->red_zone(), 2123 Shared_DirtyCardQ_lock); 2124 2125 if (G1DeferredRSUpdate) { 2126 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2127 DirtyCardQ_CBL_mon, 2128 DirtyCardQ_FL_lock, 2129 -1, // never trigger processing 2130 -1, // no limit on length 2131 Shared_DirtyCardQ_lock, 2132 &JavaThread::dirty_card_queue_set()); 2133 } 2134 2135 // Initialize the card queue set used to hold cards containing 2136 // references into the collection set. 2137 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2138 DirtyCardQ_CBL_mon, 2139 DirtyCardQ_FL_lock, 2140 -1, // never trigger processing 2141 -1, // no limit on length 2142 Shared_DirtyCardQ_lock, 2143 &JavaThread::dirty_card_queue_set()); 2144 2145 // In case we're keeping closure specialization stats, initialize those 2146 // counts and that mechanism. 2147 SpecializationStats::clear(); 2148 2149 // Here we allocate the dummy full region that is required by the 2150 // G1AllocRegion class. If we don't pass an address in the reserved 2151 // space here, lots of asserts fire. 2152 2153 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2154 _g1_reserved.start()); 2155 // We'll re-use the same region whether the alloc region will 2156 // require BOT updates or not and, if it doesn't, then a non-young 2157 // region will complain that it cannot support allocations without 2158 // BOT updates. So we'll tag the dummy region as young to avoid that. 2159 dummy_region->set_young(); 2160 // Make sure it's full. 2161 dummy_region->set_top(dummy_region->end()); 2162 G1AllocRegion::setup(this, dummy_region); 2163 2164 init_mutator_alloc_region(); 2165 2166 // Do create of the monitoring and management support so that 2167 // values in the heap have been properly initialized. 2168 _g1mm = new G1MonitoringSupport(this); 2169 2170 G1StringDedup::initialize(); 2171 2172 return JNI_OK; 2173 } 2174 2175 void G1CollectedHeap::stop() { 2176 // Stop all concurrent threads. We do this to make sure these threads 2177 // do not continue to execute and access resources (e.g. gclog_or_tty) 2178 // that are destroyed during shutdown. 2179 _cg1r->stop(); 2180 _cmThread->stop(); 2181 if (G1StringDedup::is_enabled()) { 2182 G1StringDedup::stop(); 2183 } 2184 } 2185 2186 void G1CollectedHeap::clear_humongous_is_live_table() { 2187 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true"); 2188 _humongous_is_live.clear(); 2189 } 2190 2191 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2192 return HeapRegion::max_region_size(); 2193 } 2194 2195 void G1CollectedHeap::ref_processing_init() { 2196 // Reference processing in G1 currently works as follows: 2197 // 2198 // * There are two reference processor instances. One is 2199 // used to record and process discovered references 2200 // during concurrent marking; the other is used to 2201 // record and process references during STW pauses 2202 // (both full and incremental). 2203 // * Both ref processors need to 'span' the entire heap as 2204 // the regions in the collection set may be dotted around. 2205 // 2206 // * For the concurrent marking ref processor: 2207 // * Reference discovery is enabled at initial marking. 2208 // * Reference discovery is disabled and the discovered 2209 // references processed etc during remarking. 2210 // * Reference discovery is MT (see below). 2211 // * Reference discovery requires a barrier (see below). 2212 // * Reference processing may or may not be MT 2213 // (depending on the value of ParallelRefProcEnabled 2214 // and ParallelGCThreads). 2215 // * A full GC disables reference discovery by the CM 2216 // ref processor and abandons any entries on it's 2217 // discovered lists. 2218 // 2219 // * For the STW processor: 2220 // * Non MT discovery is enabled at the start of a full GC. 2221 // * Processing and enqueueing during a full GC is non-MT. 2222 // * During a full GC, references are processed after marking. 2223 // 2224 // * Discovery (may or may not be MT) is enabled at the start 2225 // of an incremental evacuation pause. 2226 // * References are processed near the end of a STW evacuation pause. 2227 // * For both types of GC: 2228 // * Discovery is atomic - i.e. not concurrent. 2229 // * Reference discovery will not need a barrier. 2230 2231 SharedHeap::ref_processing_init(); 2232 MemRegion mr = reserved_region(); 2233 2234 // Concurrent Mark ref processor 2235 _ref_processor_cm = 2236 new ReferenceProcessor(mr, // span 2237 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2238 // mt processing 2239 (int) ParallelGCThreads, 2240 // degree of mt processing 2241 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2242 // mt discovery 2243 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2244 // degree of mt discovery 2245 false, 2246 // Reference discovery is not atomic 2247 &_is_alive_closure_cm); 2248 // is alive closure 2249 // (for efficiency/performance) 2250 2251 // STW ref processor 2252 _ref_processor_stw = 2253 new ReferenceProcessor(mr, // span 2254 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2255 // mt processing 2256 MAX2((int)ParallelGCThreads, 1), 2257 // degree of mt processing 2258 (ParallelGCThreads > 1), 2259 // mt discovery 2260 MAX2((int)ParallelGCThreads, 1), 2261 // degree of mt discovery 2262 true, 2263 // Reference discovery is atomic 2264 &_is_alive_closure_stw); 2265 // is alive closure 2266 // (for efficiency/performance) 2267 } 2268 2269 size_t G1CollectedHeap::capacity() const { 2270 return _g1_committed.byte_size(); 2271 } 2272 2273 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2274 assert(!hr->continuesHumongous(), "pre-condition"); 2275 hr->reset_gc_time_stamp(); 2276 if (hr->startsHumongous()) { 2277 uint first_index = hr->hrs_index() + 1; 2278 uint last_index = hr->last_hc_index(); 2279 for (uint i = first_index; i < last_index; i += 1) { 2280 HeapRegion* chr = region_at(i); 2281 assert(chr->continuesHumongous(), "sanity"); 2282 chr->reset_gc_time_stamp(); 2283 } 2284 } 2285 } 2286 2287 #ifndef PRODUCT 2288 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2289 private: 2290 unsigned _gc_time_stamp; 2291 bool _failures; 2292 2293 public: 2294 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2295 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2296 2297 virtual bool doHeapRegion(HeapRegion* hr) { 2298 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2299 if (_gc_time_stamp != region_gc_time_stamp) { 2300 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2301 "expected %d", HR_FORMAT_PARAMS(hr), 2302 region_gc_time_stamp, _gc_time_stamp); 2303 _failures = true; 2304 } 2305 return false; 2306 } 2307 2308 bool failures() { return _failures; } 2309 }; 2310 2311 void G1CollectedHeap::check_gc_time_stamps() { 2312 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2313 heap_region_iterate(&cl); 2314 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2315 } 2316 #endif // PRODUCT 2317 2318 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2319 DirtyCardQueue* into_cset_dcq, 2320 bool concurrent, 2321 uint worker_i) { 2322 // Clean cards in the hot card cache 2323 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2324 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2325 2326 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2327 int n_completed_buffers = 0; 2328 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2329 n_completed_buffers++; 2330 } 2331 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2332 dcqs.clear_n_completed_buffers(); 2333 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2334 } 2335 2336 2337 // Computes the sum of the storage used by the various regions. 2338 2339 size_t G1CollectedHeap::used() const { 2340 assert(Heap_lock->owner() != NULL, 2341 "Should be owned on this thread's behalf."); 2342 size_t result = _summary_bytes_used; 2343 // Read only once in case it is set to NULL concurrently 2344 HeapRegion* hr = _mutator_alloc_region.get(); 2345 if (hr != NULL) 2346 result += hr->used(); 2347 return result; 2348 } 2349 2350 size_t G1CollectedHeap::used_unlocked() const { 2351 size_t result = _summary_bytes_used; 2352 return result; 2353 } 2354 2355 class SumUsedClosure: public HeapRegionClosure { 2356 size_t _used; 2357 public: 2358 SumUsedClosure() : _used(0) {} 2359 bool doHeapRegion(HeapRegion* r) { 2360 if (!r->continuesHumongous()) { 2361 _used += r->used(); 2362 } 2363 return false; 2364 } 2365 size_t result() { return _used; } 2366 }; 2367 2368 size_t G1CollectedHeap::recalculate_used() const { 2369 double recalculate_used_start = os::elapsedTime(); 2370 2371 SumUsedClosure blk; 2372 heap_region_iterate(&blk); 2373 2374 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2375 return blk.result(); 2376 } 2377 2378 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2379 switch (cause) { 2380 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2381 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2382 case GCCause::_g1_humongous_allocation: return true; 2383 default: return false; 2384 } 2385 } 2386 2387 #ifndef PRODUCT 2388 void G1CollectedHeap::allocate_dummy_regions() { 2389 // Let's fill up most of the region 2390 size_t word_size = HeapRegion::GrainWords - 1024; 2391 // And as a result the region we'll allocate will be humongous. 2392 guarantee(isHumongous(word_size), "sanity"); 2393 2394 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2395 // Let's use the existing mechanism for the allocation 2396 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2397 if (dummy_obj != NULL) { 2398 MemRegion mr(dummy_obj, word_size); 2399 CollectedHeap::fill_with_object(mr); 2400 } else { 2401 // If we can't allocate once, we probably cannot allocate 2402 // again. Let's get out of the loop. 2403 break; 2404 } 2405 } 2406 } 2407 #endif // !PRODUCT 2408 2409 void G1CollectedHeap::increment_old_marking_cycles_started() { 2410 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2411 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2412 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2413 _old_marking_cycles_started, _old_marking_cycles_completed)); 2414 2415 _old_marking_cycles_started++; 2416 } 2417 2418 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2419 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2420 2421 // We assume that if concurrent == true, then the caller is a 2422 // concurrent thread that was joined the Suspendible Thread 2423 // Set. If there's ever a cheap way to check this, we should add an 2424 // assert here. 2425 2426 // Given that this method is called at the end of a Full GC or of a 2427 // concurrent cycle, and those can be nested (i.e., a Full GC can 2428 // interrupt a concurrent cycle), the number of full collections 2429 // completed should be either one (in the case where there was no 2430 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2431 // behind the number of full collections started. 2432 2433 // This is the case for the inner caller, i.e. a Full GC. 2434 assert(concurrent || 2435 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2436 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2437 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2438 "is inconsistent with _old_marking_cycles_completed = %u", 2439 _old_marking_cycles_started, _old_marking_cycles_completed)); 2440 2441 // This is the case for the outer caller, i.e. the concurrent cycle. 2442 assert(!concurrent || 2443 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2444 err_msg("for outer caller (concurrent cycle): " 2445 "_old_marking_cycles_started = %u " 2446 "is inconsistent with _old_marking_cycles_completed = %u", 2447 _old_marking_cycles_started, _old_marking_cycles_completed)); 2448 2449 _old_marking_cycles_completed += 1; 2450 2451 // We need to clear the "in_progress" flag in the CM thread before 2452 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2453 // is set) so that if a waiter requests another System.gc() it doesn't 2454 // incorrectly see that a marking cycle is still in progress. 2455 if (concurrent) { 2456 _cmThread->clear_in_progress(); 2457 } 2458 2459 // This notify_all() will ensure that a thread that called 2460 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2461 // and it's waiting for a full GC to finish will be woken up. It is 2462 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2463 FullGCCount_lock->notify_all(); 2464 } 2465 2466 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2467 _concurrent_cycle_started = true; 2468 _gc_timer_cm->register_gc_start(start_time); 2469 2470 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2471 trace_heap_before_gc(_gc_tracer_cm); 2472 } 2473 2474 void G1CollectedHeap::register_concurrent_cycle_end() { 2475 if (_concurrent_cycle_started) { 2476 if (_cm->has_aborted()) { 2477 _gc_tracer_cm->report_concurrent_mode_failure(); 2478 } 2479 2480 _gc_timer_cm->register_gc_end(); 2481 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2482 2483 _concurrent_cycle_started = false; 2484 } 2485 } 2486 2487 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2488 if (_concurrent_cycle_started) { 2489 trace_heap_after_gc(_gc_tracer_cm); 2490 } 2491 } 2492 2493 G1YCType G1CollectedHeap::yc_type() { 2494 bool is_young = g1_policy()->gcs_are_young(); 2495 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2496 bool is_during_mark = mark_in_progress(); 2497 2498 if (is_initial_mark) { 2499 return InitialMark; 2500 } else if (is_during_mark) { 2501 return DuringMark; 2502 } else if (is_young) { 2503 return Normal; 2504 } else { 2505 return Mixed; 2506 } 2507 } 2508 2509 void G1CollectedHeap::collect(GCCause::Cause cause) { 2510 assert_heap_not_locked(); 2511 2512 unsigned int gc_count_before; 2513 unsigned int old_marking_count_before; 2514 bool retry_gc; 2515 2516 do { 2517 retry_gc = false; 2518 2519 { 2520 MutexLocker ml(Heap_lock); 2521 2522 // Read the GC count while holding the Heap_lock 2523 gc_count_before = total_collections(); 2524 old_marking_count_before = _old_marking_cycles_started; 2525 } 2526 2527 if (should_do_concurrent_full_gc(cause)) { 2528 // Schedule an initial-mark evacuation pause that will start a 2529 // concurrent cycle. We're setting word_size to 0 which means that 2530 // we are not requesting a post-GC allocation. 2531 VM_G1IncCollectionPause op(gc_count_before, 2532 0, /* word_size */ 2533 true, /* should_initiate_conc_mark */ 2534 g1_policy()->max_pause_time_ms(), 2535 cause); 2536 2537 VMThread::execute(&op); 2538 if (!op.pause_succeeded()) { 2539 if (old_marking_count_before == _old_marking_cycles_started) { 2540 retry_gc = op.should_retry_gc(); 2541 } else { 2542 // A Full GC happened while we were trying to schedule the 2543 // initial-mark GC. No point in starting a new cycle given 2544 // that the whole heap was collected anyway. 2545 } 2546 2547 if (retry_gc) { 2548 if (GC_locker::is_active_and_needs_gc()) { 2549 GC_locker::stall_until_clear(); 2550 } 2551 } 2552 } 2553 } else { 2554 if (cause == GCCause::_gc_locker 2555 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2556 2557 // Schedule a standard evacuation pause. We're setting word_size 2558 // to 0 which means that we are not requesting a post-GC allocation. 2559 VM_G1IncCollectionPause op(gc_count_before, 2560 0, /* word_size */ 2561 false, /* should_initiate_conc_mark */ 2562 g1_policy()->max_pause_time_ms(), 2563 cause); 2564 VMThread::execute(&op); 2565 } else { 2566 // Schedule a Full GC. 2567 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2568 VMThread::execute(&op); 2569 } 2570 } 2571 } while (retry_gc); 2572 } 2573 2574 bool G1CollectedHeap::is_in(const void* p) const { 2575 if (_g1_committed.contains(p)) { 2576 // Given that we know that p is in the committed space, 2577 // heap_region_containing_raw() should successfully 2578 // return the containing region. 2579 HeapRegion* hr = heap_region_containing_raw(p); 2580 return hr->is_in(p); 2581 } else { 2582 return false; 2583 } 2584 } 2585 2586 // Iteration functions. 2587 2588 // Iterates an OopClosure over all ref-containing fields of objects 2589 // within a HeapRegion. 2590 2591 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2592 MemRegion _mr; 2593 ExtendedOopClosure* _cl; 2594 public: 2595 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2596 : _mr(mr), _cl(cl) {} 2597 bool doHeapRegion(HeapRegion* r) { 2598 if (!r->continuesHumongous()) { 2599 r->oop_iterate(_cl); 2600 } 2601 return false; 2602 } 2603 }; 2604 2605 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2606 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2607 heap_region_iterate(&blk); 2608 } 2609 2610 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2611 IterateOopClosureRegionClosure blk(mr, cl); 2612 heap_region_iterate(&blk); 2613 } 2614 2615 // Iterates an ObjectClosure over all objects within a HeapRegion. 2616 2617 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2618 ObjectClosure* _cl; 2619 public: 2620 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2621 bool doHeapRegion(HeapRegion* r) { 2622 if (! r->continuesHumongous()) { 2623 r->object_iterate(_cl); 2624 } 2625 return false; 2626 } 2627 }; 2628 2629 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2630 IterateObjectClosureRegionClosure blk(cl); 2631 heap_region_iterate(&blk); 2632 } 2633 2634 // Calls a SpaceClosure on a HeapRegion. 2635 2636 class SpaceClosureRegionClosure: public HeapRegionClosure { 2637 SpaceClosure* _cl; 2638 public: 2639 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2640 bool doHeapRegion(HeapRegion* r) { 2641 _cl->do_space(r); 2642 return false; 2643 } 2644 }; 2645 2646 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2647 SpaceClosureRegionClosure blk(cl); 2648 heap_region_iterate(&blk); 2649 } 2650 2651 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2652 _hrs.iterate(cl); 2653 } 2654 2655 void 2656 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2657 uint worker_id, 2658 uint no_of_par_workers, 2659 jint claim_value) { 2660 const uint regions = n_regions(); 2661 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2662 no_of_par_workers : 2663 1); 2664 assert(UseDynamicNumberOfGCThreads || 2665 no_of_par_workers == workers()->total_workers(), 2666 "Non dynamic should use fixed number of workers"); 2667 // try to spread out the starting points of the workers 2668 const HeapRegion* start_hr = 2669 start_region_for_worker(worker_id, no_of_par_workers); 2670 const uint start_index = start_hr->hrs_index(); 2671 2672 // each worker will actually look at all regions 2673 for (uint count = 0; count < regions; ++count) { 2674 const uint index = (start_index + count) % regions; 2675 assert(0 <= index && index < regions, "sanity"); 2676 HeapRegion* r = region_at(index); 2677 // we'll ignore "continues humongous" regions (we'll process them 2678 // when we come across their corresponding "start humongous" 2679 // region) and regions already claimed 2680 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2681 continue; 2682 } 2683 // OK, try to claim it 2684 if (r->claimHeapRegion(claim_value)) { 2685 // success! 2686 assert(!r->continuesHumongous(), "sanity"); 2687 if (r->startsHumongous()) { 2688 // If the region is "starts humongous" we'll iterate over its 2689 // "continues humongous" first; in fact we'll do them 2690 // first. The order is important. In on case, calling the 2691 // closure on the "starts humongous" region might de-allocate 2692 // and clear all its "continues humongous" regions and, as a 2693 // result, we might end up processing them twice. So, we'll do 2694 // them first (notice: most closures will ignore them anyway) and 2695 // then we'll do the "starts humongous" region. 2696 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2697 HeapRegion* chr = region_at(ch_index); 2698 2699 // if the region has already been claimed or it's not 2700 // "continues humongous" we're done 2701 if (chr->claim_value() == claim_value || 2702 !chr->continuesHumongous()) { 2703 break; 2704 } 2705 2706 // No one should have claimed it directly. We can given 2707 // that we claimed its "starts humongous" region. 2708 assert(chr->claim_value() != claim_value, "sanity"); 2709 assert(chr->humongous_start_region() == r, "sanity"); 2710 2711 if (chr->claimHeapRegion(claim_value)) { 2712 // we should always be able to claim it; no one else should 2713 // be trying to claim this region 2714 2715 bool res2 = cl->doHeapRegion(chr); 2716 assert(!res2, "Should not abort"); 2717 2718 // Right now, this holds (i.e., no closure that actually 2719 // does something with "continues humongous" regions 2720 // clears them). We might have to weaken it in the future, 2721 // but let's leave these two asserts here for extra safety. 2722 assert(chr->continuesHumongous(), "should still be the case"); 2723 assert(chr->humongous_start_region() == r, "sanity"); 2724 } else { 2725 guarantee(false, "we should not reach here"); 2726 } 2727 } 2728 } 2729 2730 assert(!r->continuesHumongous(), "sanity"); 2731 bool res = cl->doHeapRegion(r); 2732 assert(!res, "Should not abort"); 2733 } 2734 } 2735 } 2736 2737 class ResetClaimValuesClosure: public HeapRegionClosure { 2738 public: 2739 bool doHeapRegion(HeapRegion* r) { 2740 r->set_claim_value(HeapRegion::InitialClaimValue); 2741 return false; 2742 } 2743 }; 2744 2745 void G1CollectedHeap::reset_heap_region_claim_values() { 2746 ResetClaimValuesClosure blk; 2747 heap_region_iterate(&blk); 2748 } 2749 2750 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2751 ResetClaimValuesClosure blk; 2752 collection_set_iterate(&blk); 2753 } 2754 2755 #ifdef ASSERT 2756 // This checks whether all regions in the heap have the correct claim 2757 // value. I also piggy-backed on this a check to ensure that the 2758 // humongous_start_region() information on "continues humongous" 2759 // regions is correct. 2760 2761 class CheckClaimValuesClosure : public HeapRegionClosure { 2762 private: 2763 jint _claim_value; 2764 uint _failures; 2765 HeapRegion* _sh_region; 2766 2767 public: 2768 CheckClaimValuesClosure(jint claim_value) : 2769 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2770 bool doHeapRegion(HeapRegion* r) { 2771 if (r->claim_value() != _claim_value) { 2772 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2773 "claim value = %d, should be %d", 2774 HR_FORMAT_PARAMS(r), 2775 r->claim_value(), _claim_value); 2776 ++_failures; 2777 } 2778 if (!r->isHumongous()) { 2779 _sh_region = NULL; 2780 } else if (r->startsHumongous()) { 2781 _sh_region = r; 2782 } else if (r->continuesHumongous()) { 2783 if (r->humongous_start_region() != _sh_region) { 2784 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2785 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2786 HR_FORMAT_PARAMS(r), 2787 r->humongous_start_region(), 2788 _sh_region); 2789 ++_failures; 2790 } 2791 } 2792 return false; 2793 } 2794 uint failures() { return _failures; } 2795 }; 2796 2797 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2798 CheckClaimValuesClosure cl(claim_value); 2799 heap_region_iterate(&cl); 2800 return cl.failures() == 0; 2801 } 2802 2803 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2804 private: 2805 jint _claim_value; 2806 uint _failures; 2807 2808 public: 2809 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2810 _claim_value(claim_value), _failures(0) { } 2811 2812 uint failures() { return _failures; } 2813 2814 bool doHeapRegion(HeapRegion* hr) { 2815 assert(hr->in_collection_set(), "how?"); 2816 assert(!hr->isHumongous(), "H-region in CSet"); 2817 if (hr->claim_value() != _claim_value) { 2818 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2819 "claim value = %d, should be %d", 2820 HR_FORMAT_PARAMS(hr), 2821 hr->claim_value(), _claim_value); 2822 _failures += 1; 2823 } 2824 return false; 2825 } 2826 }; 2827 2828 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2829 CheckClaimValuesInCSetHRClosure cl(claim_value); 2830 collection_set_iterate(&cl); 2831 return cl.failures() == 0; 2832 } 2833 #endif // ASSERT 2834 2835 // Clear the cached CSet starting regions and (more importantly) 2836 // the time stamps. Called when we reset the GC time stamp. 2837 void G1CollectedHeap::clear_cset_start_regions() { 2838 assert(_worker_cset_start_region != NULL, "sanity"); 2839 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2840 2841 int n_queues = MAX2((int)ParallelGCThreads, 1); 2842 for (int i = 0; i < n_queues; i++) { 2843 _worker_cset_start_region[i] = NULL; 2844 _worker_cset_start_region_time_stamp[i] = 0; 2845 } 2846 } 2847 2848 // Given the id of a worker, obtain or calculate a suitable 2849 // starting region for iterating over the current collection set. 2850 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2851 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2852 2853 HeapRegion* result = NULL; 2854 unsigned gc_time_stamp = get_gc_time_stamp(); 2855 2856 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2857 // Cached starting region for current worker was set 2858 // during the current pause - so it's valid. 2859 // Note: the cached starting heap region may be NULL 2860 // (when the collection set is empty). 2861 result = _worker_cset_start_region[worker_i]; 2862 assert(result == NULL || result->in_collection_set(), "sanity"); 2863 return result; 2864 } 2865 2866 // The cached entry was not valid so let's calculate 2867 // a suitable starting heap region for this worker. 2868 2869 // We want the parallel threads to start their collection 2870 // set iteration at different collection set regions to 2871 // avoid contention. 2872 // If we have: 2873 // n collection set regions 2874 // p threads 2875 // Then thread t will start at region floor ((t * n) / p) 2876 2877 result = g1_policy()->collection_set(); 2878 if (G1CollectedHeap::use_parallel_gc_threads()) { 2879 uint cs_size = g1_policy()->cset_region_length(); 2880 uint active_workers = workers()->active_workers(); 2881 assert(UseDynamicNumberOfGCThreads || 2882 active_workers == workers()->total_workers(), 2883 "Unless dynamic should use total workers"); 2884 2885 uint end_ind = (cs_size * worker_i) / active_workers; 2886 uint start_ind = 0; 2887 2888 if (worker_i > 0 && 2889 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2890 // Previous workers starting region is valid 2891 // so let's iterate from there 2892 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2893 result = _worker_cset_start_region[worker_i - 1]; 2894 } 2895 2896 for (uint i = start_ind; i < end_ind; i++) { 2897 result = result->next_in_collection_set(); 2898 } 2899 } 2900 2901 // Note: the calculated starting heap region may be NULL 2902 // (when the collection set is empty). 2903 assert(result == NULL || result->in_collection_set(), "sanity"); 2904 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2905 "should be updated only once per pause"); 2906 _worker_cset_start_region[worker_i] = result; 2907 OrderAccess::storestore(); 2908 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2909 return result; 2910 } 2911 2912 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2913 uint no_of_par_workers) { 2914 uint worker_num = 2915 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2916 assert(UseDynamicNumberOfGCThreads || 2917 no_of_par_workers == workers()->total_workers(), 2918 "Non dynamic should use fixed number of workers"); 2919 const uint start_index = n_regions() * worker_i / worker_num; 2920 return region_at(start_index); 2921 } 2922 2923 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2924 HeapRegion* r = g1_policy()->collection_set(); 2925 while (r != NULL) { 2926 HeapRegion* next = r->next_in_collection_set(); 2927 if (cl->doHeapRegion(r)) { 2928 cl->incomplete(); 2929 return; 2930 } 2931 r = next; 2932 } 2933 } 2934 2935 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2936 HeapRegionClosure *cl) { 2937 if (r == NULL) { 2938 // The CSet is empty so there's nothing to do. 2939 return; 2940 } 2941 2942 assert(r->in_collection_set(), 2943 "Start region must be a member of the collection set."); 2944 HeapRegion* cur = r; 2945 while (cur != NULL) { 2946 HeapRegion* next = cur->next_in_collection_set(); 2947 if (cl->doHeapRegion(cur) && false) { 2948 cl->incomplete(); 2949 return; 2950 } 2951 cur = next; 2952 } 2953 cur = g1_policy()->collection_set(); 2954 while (cur != r) { 2955 HeapRegion* next = cur->next_in_collection_set(); 2956 if (cl->doHeapRegion(cur) && false) { 2957 cl->incomplete(); 2958 return; 2959 } 2960 cur = next; 2961 } 2962 } 2963 2964 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2965 // We're not using an iterator given that it will wrap around when 2966 // it reaches the last region and this is not what we want here. 2967 for (uint index = from->hrs_index() + 1; index < n_regions(); index++) { 2968 HeapRegion* hr = region_at(index); 2969 if (!hr->isHumongous()) { 2970 return hr; 2971 } 2972 } 2973 return NULL; 2974 } 2975 2976 Space* G1CollectedHeap::space_containing(const void* addr) const { 2977 return heap_region_containing(addr); 2978 } 2979 2980 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2981 Space* sp = space_containing(addr); 2982 return sp->block_start(addr); 2983 } 2984 2985 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2986 Space* sp = space_containing(addr); 2987 return sp->block_size(addr); 2988 } 2989 2990 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2991 Space* sp = space_containing(addr); 2992 return sp->block_is_obj(addr); 2993 } 2994 2995 bool G1CollectedHeap::supports_tlab_allocation() const { 2996 return true; 2997 } 2998 2999 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 3000 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 3001 } 3002 3003 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 3004 return young_list()->eden_used_bytes(); 3005 } 3006 3007 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 3008 // must be smaller than the humongous object limit. 3009 size_t G1CollectedHeap::max_tlab_size() const { 3010 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 3011 } 3012 3013 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 3014 // Return the remaining space in the cur alloc region, but not less than 3015 // the min TLAB size. 3016 3017 // Also, this value can be at most the humongous object threshold, 3018 // since we can't allow tlabs to grow big enough to accommodate 3019 // humongous objects. 3020 3021 HeapRegion* hr = _mutator_alloc_region.get(); 3022 size_t max_tlab = max_tlab_size() * wordSize; 3023 if (hr == NULL) { 3024 return max_tlab; 3025 } else { 3026 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 3027 } 3028 } 3029 3030 size_t G1CollectedHeap::max_capacity() const { 3031 return _g1_reserved.byte_size(); 3032 } 3033 3034 jlong G1CollectedHeap::millis_since_last_gc() { 3035 // assert(false, "NYI"); 3036 return 0; 3037 } 3038 3039 void G1CollectedHeap::prepare_for_verify() { 3040 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3041 ensure_parsability(false); 3042 } 3043 g1_rem_set()->prepare_for_verify(); 3044 } 3045 3046 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3047 VerifyOption vo) { 3048 switch (vo) { 3049 case VerifyOption_G1UsePrevMarking: 3050 return hr->obj_allocated_since_prev_marking(obj); 3051 case VerifyOption_G1UseNextMarking: 3052 return hr->obj_allocated_since_next_marking(obj); 3053 case VerifyOption_G1UseMarkWord: 3054 return false; 3055 default: 3056 ShouldNotReachHere(); 3057 } 3058 return false; // keep some compilers happy 3059 } 3060 3061 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3062 switch (vo) { 3063 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3064 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3065 case VerifyOption_G1UseMarkWord: return NULL; 3066 default: ShouldNotReachHere(); 3067 } 3068 return NULL; // keep some compilers happy 3069 } 3070 3071 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3072 switch (vo) { 3073 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3074 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3075 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3076 default: ShouldNotReachHere(); 3077 } 3078 return false; // keep some compilers happy 3079 } 3080 3081 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3082 switch (vo) { 3083 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3084 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3085 case VerifyOption_G1UseMarkWord: return "NONE"; 3086 default: ShouldNotReachHere(); 3087 } 3088 return NULL; // keep some compilers happy 3089 } 3090 3091 class VerifyRootsClosure: public OopClosure { 3092 private: 3093 G1CollectedHeap* _g1h; 3094 VerifyOption _vo; 3095 bool _failures; 3096 public: 3097 // _vo == UsePrevMarking -> use "prev" marking information, 3098 // _vo == UseNextMarking -> use "next" marking information, 3099 // _vo == UseMarkWord -> use mark word from object header. 3100 VerifyRootsClosure(VerifyOption vo) : 3101 _g1h(G1CollectedHeap::heap()), 3102 _vo(vo), 3103 _failures(false) { } 3104 3105 bool failures() { return _failures; } 3106 3107 template <class T> void do_oop_nv(T* p) { 3108 T heap_oop = oopDesc::load_heap_oop(p); 3109 if (!oopDesc::is_null(heap_oop)) { 3110 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3111 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3112 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3113 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3114 if (_vo == VerifyOption_G1UseMarkWord) { 3115 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3116 } 3117 obj->print_on(gclog_or_tty); 3118 _failures = true; 3119 } 3120 } 3121 } 3122 3123 void do_oop(oop* p) { do_oop_nv(p); } 3124 void do_oop(narrowOop* p) { do_oop_nv(p); } 3125 }; 3126 3127 class G1VerifyCodeRootOopClosure: public OopClosure { 3128 G1CollectedHeap* _g1h; 3129 OopClosure* _root_cl; 3130 nmethod* _nm; 3131 VerifyOption _vo; 3132 bool _failures; 3133 3134 template <class T> void do_oop_work(T* p) { 3135 // First verify that this root is live 3136 _root_cl->do_oop(p); 3137 3138 if (!G1VerifyHeapRegionCodeRoots) { 3139 // We're not verifying the code roots attached to heap region. 3140 return; 3141 } 3142 3143 // Don't check the code roots during marking verification in a full GC 3144 if (_vo == VerifyOption_G1UseMarkWord) { 3145 return; 3146 } 3147 3148 // Now verify that the current nmethod (which contains p) is 3149 // in the code root list of the heap region containing the 3150 // object referenced by p. 3151 3152 T heap_oop = oopDesc::load_heap_oop(p); 3153 if (!oopDesc::is_null(heap_oop)) { 3154 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3155 3156 // Now fetch the region containing the object 3157 HeapRegion* hr = _g1h->heap_region_containing(obj); 3158 HeapRegionRemSet* hrrs = hr->rem_set(); 3159 // Verify that the strong code root list for this region 3160 // contains the nmethod 3161 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3162 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3163 "from nmethod "PTR_FORMAT" not in strong " 3164 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3165 p, _nm, hr->bottom(), hr->end()); 3166 _failures = true; 3167 } 3168 } 3169 } 3170 3171 public: 3172 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3173 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3174 3175 void do_oop(oop* p) { do_oop_work(p); } 3176 void do_oop(narrowOop* p) { do_oop_work(p); } 3177 3178 void set_nmethod(nmethod* nm) { _nm = nm; } 3179 bool failures() { return _failures; } 3180 }; 3181 3182 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3183 G1VerifyCodeRootOopClosure* _oop_cl; 3184 3185 public: 3186 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3187 _oop_cl(oop_cl) {} 3188 3189 void do_code_blob(CodeBlob* cb) { 3190 nmethod* nm = cb->as_nmethod_or_null(); 3191 if (nm != NULL) { 3192 _oop_cl->set_nmethod(nm); 3193 nm->oops_do(_oop_cl); 3194 } 3195 } 3196 }; 3197 3198 class YoungRefCounterClosure : public OopClosure { 3199 G1CollectedHeap* _g1h; 3200 int _count; 3201 public: 3202 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3203 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3204 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3205 3206 int count() { return _count; } 3207 void reset_count() { _count = 0; }; 3208 }; 3209 3210 class VerifyKlassClosure: public KlassClosure { 3211 YoungRefCounterClosure _young_ref_counter_closure; 3212 OopClosure *_oop_closure; 3213 public: 3214 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3215 void do_klass(Klass* k) { 3216 k->oops_do(_oop_closure); 3217 3218 _young_ref_counter_closure.reset_count(); 3219 k->oops_do(&_young_ref_counter_closure); 3220 if (_young_ref_counter_closure.count() > 0) { 3221 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 3222 } 3223 } 3224 }; 3225 3226 class VerifyLivenessOopClosure: public OopClosure { 3227 G1CollectedHeap* _g1h; 3228 VerifyOption _vo; 3229 public: 3230 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3231 _g1h(g1h), _vo(vo) 3232 { } 3233 void do_oop(narrowOop *p) { do_oop_work(p); } 3234 void do_oop( oop *p) { do_oop_work(p); } 3235 3236 template <class T> void do_oop_work(T *p) { 3237 oop obj = oopDesc::load_decode_heap_oop(p); 3238 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3239 "Dead object referenced by a not dead object"); 3240 } 3241 }; 3242 3243 class VerifyObjsInRegionClosure: public ObjectClosure { 3244 private: 3245 G1CollectedHeap* _g1h; 3246 size_t _live_bytes; 3247 HeapRegion *_hr; 3248 VerifyOption _vo; 3249 public: 3250 // _vo == UsePrevMarking -> use "prev" marking information, 3251 // _vo == UseNextMarking -> use "next" marking information, 3252 // _vo == UseMarkWord -> use mark word from object header. 3253 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3254 : _live_bytes(0), _hr(hr), _vo(vo) { 3255 _g1h = G1CollectedHeap::heap(); 3256 } 3257 void do_object(oop o) { 3258 VerifyLivenessOopClosure isLive(_g1h, _vo); 3259 assert(o != NULL, "Huh?"); 3260 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3261 // If the object is alive according to the mark word, 3262 // then verify that the marking information agrees. 3263 // Note we can't verify the contra-positive of the 3264 // above: if the object is dead (according to the mark 3265 // word), it may not be marked, or may have been marked 3266 // but has since became dead, or may have been allocated 3267 // since the last marking. 3268 if (_vo == VerifyOption_G1UseMarkWord) { 3269 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3270 } 3271 3272 o->oop_iterate_no_header(&isLive); 3273 if (!_hr->obj_allocated_since_prev_marking(o)) { 3274 size_t obj_size = o->size(); // Make sure we don't overflow 3275 _live_bytes += (obj_size * HeapWordSize); 3276 } 3277 } 3278 } 3279 size_t live_bytes() { return _live_bytes; } 3280 }; 3281 3282 class PrintObjsInRegionClosure : public ObjectClosure { 3283 HeapRegion *_hr; 3284 G1CollectedHeap *_g1; 3285 public: 3286 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3287 _g1 = G1CollectedHeap::heap(); 3288 }; 3289 3290 void do_object(oop o) { 3291 if (o != NULL) { 3292 HeapWord *start = (HeapWord *) o; 3293 size_t word_sz = o->size(); 3294 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3295 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3296 (void*) o, word_sz, 3297 _g1->isMarkedPrev(o), 3298 _g1->isMarkedNext(o), 3299 _hr->obj_allocated_since_prev_marking(o)); 3300 HeapWord *end = start + word_sz; 3301 HeapWord *cur; 3302 int *val; 3303 for (cur = start; cur < end; cur++) { 3304 val = (int *) cur; 3305 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3306 } 3307 } 3308 } 3309 }; 3310 3311 class VerifyRegionClosure: public HeapRegionClosure { 3312 private: 3313 bool _par; 3314 VerifyOption _vo; 3315 bool _failures; 3316 public: 3317 // _vo == UsePrevMarking -> use "prev" marking information, 3318 // _vo == UseNextMarking -> use "next" marking information, 3319 // _vo == UseMarkWord -> use mark word from object header. 3320 VerifyRegionClosure(bool par, VerifyOption vo) 3321 : _par(par), 3322 _vo(vo), 3323 _failures(false) {} 3324 3325 bool failures() { 3326 return _failures; 3327 } 3328 3329 bool doHeapRegion(HeapRegion* r) { 3330 if (!r->continuesHumongous()) { 3331 bool failures = false; 3332 r->verify(_vo, &failures); 3333 if (failures) { 3334 _failures = true; 3335 } else { 3336 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3337 r->object_iterate(¬_dead_yet_cl); 3338 if (_vo != VerifyOption_G1UseNextMarking) { 3339 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3340 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3341 "max_live_bytes "SIZE_FORMAT" " 3342 "< calculated "SIZE_FORMAT, 3343 r->bottom(), r->end(), 3344 r->max_live_bytes(), 3345 not_dead_yet_cl.live_bytes()); 3346 _failures = true; 3347 } 3348 } else { 3349 // When vo == UseNextMarking we cannot currently do a sanity 3350 // check on the live bytes as the calculation has not been 3351 // finalized yet. 3352 } 3353 } 3354 } 3355 return false; // stop the region iteration if we hit a failure 3356 } 3357 }; 3358 3359 // This is the task used for parallel verification of the heap regions 3360 3361 class G1ParVerifyTask: public AbstractGangTask { 3362 private: 3363 G1CollectedHeap* _g1h; 3364 VerifyOption _vo; 3365 bool _failures; 3366 3367 public: 3368 // _vo == UsePrevMarking -> use "prev" marking information, 3369 // _vo == UseNextMarking -> use "next" marking information, 3370 // _vo == UseMarkWord -> use mark word from object header. 3371 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3372 AbstractGangTask("Parallel verify task"), 3373 _g1h(g1h), 3374 _vo(vo), 3375 _failures(false) { } 3376 3377 bool failures() { 3378 return _failures; 3379 } 3380 3381 void work(uint worker_id) { 3382 HandleMark hm; 3383 VerifyRegionClosure blk(true, _vo); 3384 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3385 _g1h->workers()->active_workers(), 3386 HeapRegion::ParVerifyClaimValue); 3387 if (blk.failures()) { 3388 _failures = true; 3389 } 3390 } 3391 }; 3392 3393 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3394 if (SafepointSynchronize::is_at_safepoint()) { 3395 assert(Thread::current()->is_VM_thread(), 3396 "Expected to be executed serially by the VM thread at this point"); 3397 3398 if (!silent) { gclog_or_tty->print("Roots "); } 3399 VerifyRootsClosure rootsCl(vo); 3400 VerifyKlassClosure klassCl(this, &rootsCl); 3401 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3402 3403 // We apply the relevant closures to all the oops in the 3404 // system dictionary, class loader data graph, the string table 3405 // and the nmethods in the code cache. 3406 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3407 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3408 3409 process_all_roots(true, // activate StrongRootsScope 3410 SO_AllCodeCache, // roots scanning options 3411 &rootsCl, 3412 &cldCl, 3413 &blobsCl); 3414 3415 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3416 3417 if (vo != VerifyOption_G1UseMarkWord) { 3418 // If we're verifying during a full GC then the region sets 3419 // will have been torn down at the start of the GC. Therefore 3420 // verifying the region sets will fail. So we only verify 3421 // the region sets when not in a full GC. 3422 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3423 verify_region_sets(); 3424 } 3425 3426 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3427 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3428 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3429 "sanity check"); 3430 3431 G1ParVerifyTask task(this, vo); 3432 assert(UseDynamicNumberOfGCThreads || 3433 workers()->active_workers() == workers()->total_workers(), 3434 "If not dynamic should be using all the workers"); 3435 int n_workers = workers()->active_workers(); 3436 set_par_threads(n_workers); 3437 workers()->run_task(&task); 3438 set_par_threads(0); 3439 if (task.failures()) { 3440 failures = true; 3441 } 3442 3443 // Checks that the expected amount of parallel work was done. 3444 // The implication is that n_workers is > 0. 3445 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3446 "sanity check"); 3447 3448 reset_heap_region_claim_values(); 3449 3450 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3451 "sanity check"); 3452 } else { 3453 VerifyRegionClosure blk(false, vo); 3454 heap_region_iterate(&blk); 3455 if (blk.failures()) { 3456 failures = true; 3457 } 3458 } 3459 if (!silent) gclog_or_tty->print("RemSet "); 3460 rem_set()->verify(); 3461 3462 if (G1StringDedup::is_enabled()) { 3463 if (!silent) gclog_or_tty->print("StrDedup "); 3464 G1StringDedup::verify(); 3465 } 3466 3467 if (failures) { 3468 gclog_or_tty->print_cr("Heap:"); 3469 // It helps to have the per-region information in the output to 3470 // help us track down what went wrong. This is why we call 3471 // print_extended_on() instead of print_on(). 3472 print_extended_on(gclog_or_tty); 3473 gclog_or_tty->cr(); 3474 #ifndef PRODUCT 3475 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3476 concurrent_mark()->print_reachable("at-verification-failure", 3477 vo, false /* all */); 3478 } 3479 #endif 3480 gclog_or_tty->flush(); 3481 } 3482 guarantee(!failures, "there should not have been any failures"); 3483 } else { 3484 if (!silent) { 3485 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3486 if (G1StringDedup::is_enabled()) { 3487 gclog_or_tty->print(", StrDedup"); 3488 } 3489 gclog_or_tty->print(") "); 3490 } 3491 } 3492 } 3493 3494 void G1CollectedHeap::verify(bool silent) { 3495 verify(silent, VerifyOption_G1UsePrevMarking); 3496 } 3497 3498 double G1CollectedHeap::verify(bool guard, const char* msg) { 3499 double verify_time_ms = 0.0; 3500 3501 if (guard && total_collections() >= VerifyGCStartAt) { 3502 double verify_start = os::elapsedTime(); 3503 HandleMark hm; // Discard invalid handles created during verification 3504 prepare_for_verify(); 3505 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3506 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3507 } 3508 3509 return verify_time_ms; 3510 } 3511 3512 void G1CollectedHeap::verify_before_gc() { 3513 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3514 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3515 } 3516 3517 void G1CollectedHeap::verify_after_gc() { 3518 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3519 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3520 } 3521 3522 class PrintRegionClosure: public HeapRegionClosure { 3523 outputStream* _st; 3524 public: 3525 PrintRegionClosure(outputStream* st) : _st(st) {} 3526 bool doHeapRegion(HeapRegion* r) { 3527 r->print_on(_st); 3528 return false; 3529 } 3530 }; 3531 3532 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3533 const HeapRegion* hr, 3534 const VerifyOption vo) const { 3535 switch (vo) { 3536 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3537 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3538 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3539 default: ShouldNotReachHere(); 3540 } 3541 return false; // keep some compilers happy 3542 } 3543 3544 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3545 const VerifyOption vo) const { 3546 switch (vo) { 3547 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3548 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3549 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3550 default: ShouldNotReachHere(); 3551 } 3552 return false; // keep some compilers happy 3553 } 3554 3555 void G1CollectedHeap::print_on(outputStream* st) const { 3556 st->print(" %-20s", "garbage-first heap"); 3557 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3558 capacity()/K, used_unlocked()/K); 3559 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3560 _g1_storage.low_boundary(), 3561 _g1_storage.high(), 3562 _g1_storage.high_boundary()); 3563 st->cr(); 3564 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3565 uint young_regions = _young_list->length(); 3566 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3567 (size_t) young_regions * HeapRegion::GrainBytes / K); 3568 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3569 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3570 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3571 st->cr(); 3572 MetaspaceAux::print_on(st); 3573 } 3574 3575 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3576 print_on(st); 3577 3578 // Print the per-region information. 3579 st->cr(); 3580 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3581 "HS=humongous(starts), HC=humongous(continues), " 3582 "CS=collection set, F=free, TS=gc time stamp, " 3583 "PTAMS=previous top-at-mark-start, " 3584 "NTAMS=next top-at-mark-start)"); 3585 PrintRegionClosure blk(st); 3586 heap_region_iterate(&blk); 3587 } 3588 3589 void G1CollectedHeap::print_on_error(outputStream* st) const { 3590 this->CollectedHeap::print_on_error(st); 3591 3592 if (_cm != NULL) { 3593 st->cr(); 3594 _cm->print_on_error(st); 3595 } 3596 } 3597 3598 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3599 if (G1CollectedHeap::use_parallel_gc_threads()) { 3600 workers()->print_worker_threads_on(st); 3601 } 3602 _cmThread->print_on(st); 3603 st->cr(); 3604 _cm->print_worker_threads_on(st); 3605 _cg1r->print_worker_threads_on(st); 3606 if (G1StringDedup::is_enabled()) { 3607 G1StringDedup::print_worker_threads_on(st); 3608 } 3609 } 3610 3611 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3612 if (G1CollectedHeap::use_parallel_gc_threads()) { 3613 workers()->threads_do(tc); 3614 } 3615 tc->do_thread(_cmThread); 3616 _cg1r->threads_do(tc); 3617 if (G1StringDedup::is_enabled()) { 3618 G1StringDedup::threads_do(tc); 3619 } 3620 } 3621 3622 void G1CollectedHeap::print_tracing_info() const { 3623 // We'll overload this to mean "trace GC pause statistics." 3624 if (TraceYoungGenTime || TraceOldGenTime) { 3625 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3626 // to that. 3627 g1_policy()->print_tracing_info(); 3628 } 3629 if (G1SummarizeRSetStats) { 3630 g1_rem_set()->print_summary_info(); 3631 } 3632 if (G1SummarizeConcMark) { 3633 concurrent_mark()->print_summary_info(); 3634 } 3635 g1_policy()->print_yg_surv_rate_info(); 3636 SpecializationStats::print(); 3637 } 3638 3639 #ifndef PRODUCT 3640 // Helpful for debugging RSet issues. 3641 3642 class PrintRSetsClosure : public HeapRegionClosure { 3643 private: 3644 const char* _msg; 3645 size_t _occupied_sum; 3646 3647 public: 3648 bool doHeapRegion(HeapRegion* r) { 3649 HeapRegionRemSet* hrrs = r->rem_set(); 3650 size_t occupied = hrrs->occupied(); 3651 _occupied_sum += occupied; 3652 3653 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3654 HR_FORMAT_PARAMS(r)); 3655 if (occupied == 0) { 3656 gclog_or_tty->print_cr(" RSet is empty"); 3657 } else { 3658 hrrs->print(); 3659 } 3660 gclog_or_tty->print_cr("----------"); 3661 return false; 3662 } 3663 3664 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3665 gclog_or_tty->cr(); 3666 gclog_or_tty->print_cr("========================================"); 3667 gclog_or_tty->print_cr("%s", msg); 3668 gclog_or_tty->cr(); 3669 } 3670 3671 ~PrintRSetsClosure() { 3672 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3673 gclog_or_tty->print_cr("========================================"); 3674 gclog_or_tty->cr(); 3675 } 3676 }; 3677 3678 void G1CollectedHeap::print_cset_rsets() { 3679 PrintRSetsClosure cl("Printing CSet RSets"); 3680 collection_set_iterate(&cl); 3681 } 3682 3683 void G1CollectedHeap::print_all_rsets() { 3684 PrintRSetsClosure cl("Printing All RSets");; 3685 heap_region_iterate(&cl); 3686 } 3687 #endif // PRODUCT 3688 3689 G1CollectedHeap* G1CollectedHeap::heap() { 3690 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3691 "not a garbage-first heap"); 3692 return _g1h; 3693 } 3694 3695 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3696 // always_do_update_barrier = false; 3697 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3698 // Fill TLAB's and such 3699 accumulate_statistics_all_tlabs(); 3700 ensure_parsability(true); 3701 3702 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3703 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3704 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3705 } 3706 } 3707 3708 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3709 3710 if (G1SummarizeRSetStats && 3711 (G1SummarizeRSetStatsPeriod > 0) && 3712 // we are at the end of the GC. Total collections has already been increased. 3713 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3714 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3715 } 3716 3717 // FIXME: what is this about? 3718 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3719 // is set. 3720 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3721 "derived pointer present")); 3722 // always_do_update_barrier = true; 3723 3724 resize_all_tlabs(); 3725 3726 // We have just completed a GC. Update the soft reference 3727 // policy with the new heap occupancy 3728 Universe::update_heap_info_at_gc(); 3729 } 3730 3731 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3732 unsigned int gc_count_before, 3733 bool* succeeded, 3734 GCCause::Cause gc_cause) { 3735 assert_heap_not_locked_and_not_at_safepoint(); 3736 g1_policy()->record_stop_world_start(); 3737 VM_G1IncCollectionPause op(gc_count_before, 3738 word_size, 3739 false, /* should_initiate_conc_mark */ 3740 g1_policy()->max_pause_time_ms(), 3741 gc_cause); 3742 VMThread::execute(&op); 3743 3744 HeapWord* result = op.result(); 3745 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3746 assert(result == NULL || ret_succeeded, 3747 "the result should be NULL if the VM did not succeed"); 3748 *succeeded = ret_succeeded; 3749 3750 assert_heap_not_locked(); 3751 return result; 3752 } 3753 3754 void 3755 G1CollectedHeap::doConcurrentMark() { 3756 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3757 if (!_cmThread->in_progress()) { 3758 _cmThread->set_started(); 3759 CGC_lock->notify(); 3760 } 3761 } 3762 3763 size_t G1CollectedHeap::pending_card_num() { 3764 size_t extra_cards = 0; 3765 JavaThread *curr = Threads::first(); 3766 while (curr != NULL) { 3767 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3768 extra_cards += dcq.size(); 3769 curr = curr->next(); 3770 } 3771 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3772 size_t buffer_size = dcqs.buffer_size(); 3773 size_t buffer_num = dcqs.completed_buffers_num(); 3774 3775 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3776 // in bytes - not the number of 'entries'. We need to convert 3777 // into a number of cards. 3778 return (buffer_size * buffer_num + extra_cards) / oopSize; 3779 } 3780 3781 size_t G1CollectedHeap::cards_scanned() { 3782 return g1_rem_set()->cardsScanned(); 3783 } 3784 3785 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3786 HeapRegion* region = region_at(index); 3787 assert(region->startsHumongous(), "Must start a humongous object"); 3788 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3789 } 3790 3791 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3792 private: 3793 size_t _total_humongous; 3794 size_t _candidate_humongous; 3795 public: 3796 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) { 3797 } 3798 3799 virtual bool doHeapRegion(HeapRegion* r) { 3800 if (!r->startsHumongous()) { 3801 return false; 3802 } 3803 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3804 3805 uint region_idx = r->hrs_index(); 3806 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx); 3807 // Is_candidate already filters out humongous regions with some remembered set. 3808 // This will not lead to humongous object that we mistakenly keep alive because 3809 // during young collection the remembered sets will only be added to. 3810 if (is_candidate) { 3811 g1h->register_humongous_region_with_in_cset_fast_test(region_idx); 3812 _candidate_humongous++; 3813 } 3814 _total_humongous++; 3815 3816 return false; 3817 } 3818 3819 size_t total_humongous() const { return _total_humongous; } 3820 size_t candidate_humongous() const { return _candidate_humongous; } 3821 }; 3822 3823 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() { 3824 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) { 3825 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0); 3826 return; 3827 } 3828 3829 RegisterHumongousWithInCSetFastTestClosure cl; 3830 heap_region_iterate(&cl); 3831 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(), 3832 cl.candidate_humongous()); 3833 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3834 3835 if (_has_humongous_reclaim_candidates) { 3836 clear_humongous_is_live_table(); 3837 } 3838 } 3839 3840 void 3841 G1CollectedHeap::setup_surviving_young_words() { 3842 assert(_surviving_young_words == NULL, "pre-condition"); 3843 uint array_length = g1_policy()->young_cset_region_length(); 3844 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3845 if (_surviving_young_words == NULL) { 3846 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3847 "Not enough space for young surv words summary."); 3848 } 3849 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3850 #ifdef ASSERT 3851 for (uint i = 0; i < array_length; ++i) { 3852 assert( _surviving_young_words[i] == 0, "memset above" ); 3853 } 3854 #endif // !ASSERT 3855 } 3856 3857 void 3858 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3859 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3860 uint array_length = g1_policy()->young_cset_region_length(); 3861 for (uint i = 0; i < array_length; ++i) { 3862 _surviving_young_words[i] += surv_young_words[i]; 3863 } 3864 } 3865 3866 void 3867 G1CollectedHeap::cleanup_surviving_young_words() { 3868 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3869 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3870 _surviving_young_words = NULL; 3871 } 3872 3873 #ifdef ASSERT 3874 class VerifyCSetClosure: public HeapRegionClosure { 3875 public: 3876 bool doHeapRegion(HeapRegion* hr) { 3877 // Here we check that the CSet region's RSet is ready for parallel 3878 // iteration. The fields that we'll verify are only manipulated 3879 // when the region is part of a CSet and is collected. Afterwards, 3880 // we reset these fields when we clear the region's RSet (when the 3881 // region is freed) so they are ready when the region is 3882 // re-allocated. The only exception to this is if there's an 3883 // evacuation failure and instead of freeing the region we leave 3884 // it in the heap. In that case, we reset these fields during 3885 // evacuation failure handling. 3886 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3887 3888 // Here's a good place to add any other checks we'd like to 3889 // perform on CSet regions. 3890 return false; 3891 } 3892 }; 3893 #endif // ASSERT 3894 3895 #if TASKQUEUE_STATS 3896 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3897 st->print_raw_cr("GC Task Stats"); 3898 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3899 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3900 } 3901 3902 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3903 print_taskqueue_stats_hdr(st); 3904 3905 TaskQueueStats totals; 3906 const int n = workers() != NULL ? workers()->total_workers() : 1; 3907 for (int i = 0; i < n; ++i) { 3908 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3909 totals += task_queue(i)->stats; 3910 } 3911 st->print_raw("tot "); totals.print(st); st->cr(); 3912 3913 DEBUG_ONLY(totals.verify()); 3914 } 3915 3916 void G1CollectedHeap::reset_taskqueue_stats() { 3917 const int n = workers() != NULL ? workers()->total_workers() : 1; 3918 for (int i = 0; i < n; ++i) { 3919 task_queue(i)->stats.reset(); 3920 } 3921 } 3922 #endif // TASKQUEUE_STATS 3923 3924 void G1CollectedHeap::log_gc_header() { 3925 if (!G1Log::fine()) { 3926 return; 3927 } 3928 3929 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3930 3931 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3932 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3933 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3934 3935 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3936 } 3937 3938 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3939 if (!G1Log::fine()) { 3940 return; 3941 } 3942 3943 if (G1Log::finer()) { 3944 if (evacuation_failed()) { 3945 gclog_or_tty->print(" (to-space exhausted)"); 3946 } 3947 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3948 g1_policy()->phase_times()->note_gc_end(); 3949 g1_policy()->phase_times()->print(pause_time_sec); 3950 g1_policy()->print_detailed_heap_transition(); 3951 } else { 3952 if (evacuation_failed()) { 3953 gclog_or_tty->print("--"); 3954 } 3955 g1_policy()->print_heap_transition(); 3956 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3957 } 3958 gclog_or_tty->flush(); 3959 } 3960 3961 bool 3962 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3963 assert_at_safepoint(true /* should_be_vm_thread */); 3964 guarantee(!is_gc_active(), "collection is not reentrant"); 3965 3966 if (GC_locker::check_active_before_gc()) { 3967 return false; 3968 } 3969 3970 _gc_timer_stw->register_gc_start(); 3971 3972 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3973 3974 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3975 ResourceMark rm; 3976 3977 print_heap_before_gc(); 3978 trace_heap_before_gc(_gc_tracer_stw); 3979 3980 verify_region_sets_optional(); 3981 verify_dirty_young_regions(); 3982 3983 // This call will decide whether this pause is an initial-mark 3984 // pause. If it is, during_initial_mark_pause() will return true 3985 // for the duration of this pause. 3986 g1_policy()->decide_on_conc_mark_initiation(); 3987 3988 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3989 assert(!g1_policy()->during_initial_mark_pause() || 3990 g1_policy()->gcs_are_young(), "sanity"); 3991 3992 // We also do not allow mixed GCs during marking. 3993 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3994 3995 // Record whether this pause is an initial mark. When the current 3996 // thread has completed its logging output and it's safe to signal 3997 // the CM thread, the flag's value in the policy has been reset. 3998 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3999 4000 // Inner scope for scope based logging, timers, and stats collection 4001 { 4002 EvacuationInfo evacuation_info; 4003 4004 if (g1_policy()->during_initial_mark_pause()) { 4005 // We are about to start a marking cycle, so we increment the 4006 // full collection counter. 4007 increment_old_marking_cycles_started(); 4008 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 4009 } 4010 4011 _gc_tracer_stw->report_yc_type(yc_type()); 4012 4013 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 4014 4015 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 4016 workers()->active_workers() : 1); 4017 double pause_start_sec = os::elapsedTime(); 4018 g1_policy()->phase_times()->note_gc_start(active_workers); 4019 log_gc_header(); 4020 4021 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 4022 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 4023 4024 // If the secondary_free_list is not empty, append it to the 4025 // free_list. No need to wait for the cleanup operation to finish; 4026 // the region allocation code will check the secondary_free_list 4027 // and wait if necessary. If the G1StressConcRegionFreeing flag is 4028 // set, skip this step so that the region allocation code has to 4029 // get entries from the secondary_free_list. 4030 if (!G1StressConcRegionFreeing) { 4031 append_secondary_free_list_if_not_empty_with_lock(); 4032 } 4033 4034 assert(check_young_list_well_formed(), "young list should be well formed"); 4035 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 4036 "sanity check"); 4037 4038 // Don't dynamically change the number of GC threads this early. A value of 4039 // 0 is used to indicate serial work. When parallel work is done, 4040 // it will be set. 4041 4042 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 4043 IsGCActiveMark x; 4044 4045 gc_prologue(false); 4046 increment_total_collections(false /* full gc */); 4047 increment_gc_time_stamp(); 4048 4049 verify_before_gc(); 4050 4051 check_bitmaps("GC Start"); 4052 4053 COMPILER2_PRESENT(DerivedPointerTable::clear()); 4054 4055 // Please see comment in g1CollectedHeap.hpp and 4056 // G1CollectedHeap::ref_processing_init() to see how 4057 // reference processing currently works in G1. 4058 4059 // Enable discovery in the STW reference processor 4060 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 4061 true /*verify_no_refs*/); 4062 4063 { 4064 // We want to temporarily turn off discovery by the 4065 // CM ref processor, if necessary, and turn it back on 4066 // on again later if we do. Using a scoped 4067 // NoRefDiscovery object will do this. 4068 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 4069 4070 // Forget the current alloc region (we might even choose it to be part 4071 // of the collection set!). 4072 release_mutator_alloc_region(); 4073 4074 // We should call this after we retire the mutator alloc 4075 // region(s) so that all the ALLOC / RETIRE events are generated 4076 // before the start GC event. 4077 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4078 4079 // This timing is only used by the ergonomics to handle our pause target. 4080 // It is unclear why this should not include the full pause. We will 4081 // investigate this in CR 7178365. 4082 // 4083 // Preserving the old comment here if that helps the investigation: 4084 // 4085 // The elapsed time induced by the start time below deliberately elides 4086 // the possible verification above. 4087 double sample_start_time_sec = os::elapsedTime(); 4088 4089 #if YOUNG_LIST_VERBOSE 4090 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4091 _young_list->print(); 4092 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4093 #endif // YOUNG_LIST_VERBOSE 4094 4095 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4096 4097 double scan_wait_start = os::elapsedTime(); 4098 // We have to wait until the CM threads finish scanning the 4099 // root regions as it's the only way to ensure that all the 4100 // objects on them have been correctly scanned before we start 4101 // moving them during the GC. 4102 bool waited = _cm->root_regions()->wait_until_scan_finished(); 4103 double wait_time_ms = 0.0; 4104 if (waited) { 4105 double scan_wait_end = os::elapsedTime(); 4106 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4107 } 4108 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4109 4110 #if YOUNG_LIST_VERBOSE 4111 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4112 _young_list->print(); 4113 #endif // YOUNG_LIST_VERBOSE 4114 4115 if (g1_policy()->during_initial_mark_pause()) { 4116 concurrent_mark()->checkpointRootsInitialPre(); 4117 } 4118 4119 #if YOUNG_LIST_VERBOSE 4120 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4121 _young_list->print(); 4122 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4123 #endif // YOUNG_LIST_VERBOSE 4124 4125 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4126 4127 register_humongous_regions_with_in_cset_fast_test(); 4128 4129 _cm->note_start_of_gc(); 4130 // We should not verify the per-thread SATB buffers given that 4131 // we have not filtered them yet (we'll do so during the 4132 // GC). We also call this after finalize_cset() to 4133 // ensure that the CSet has been finalized. 4134 _cm->verify_no_cset_oops(true /* verify_stacks */, 4135 true /* verify_enqueued_buffers */, 4136 false /* verify_thread_buffers */, 4137 true /* verify_fingers */); 4138 4139 if (_hr_printer.is_active()) { 4140 HeapRegion* hr = g1_policy()->collection_set(); 4141 while (hr != NULL) { 4142 G1HRPrinter::RegionType type; 4143 if (!hr->is_young()) { 4144 type = G1HRPrinter::Old; 4145 } else if (hr->is_survivor()) { 4146 type = G1HRPrinter::Survivor; 4147 } else { 4148 type = G1HRPrinter::Eden; 4149 } 4150 _hr_printer.cset(hr); 4151 hr = hr->next_in_collection_set(); 4152 } 4153 } 4154 4155 #ifdef ASSERT 4156 VerifyCSetClosure cl; 4157 collection_set_iterate(&cl); 4158 #endif // ASSERT 4159 4160 setup_surviving_young_words(); 4161 4162 // Initialize the GC alloc regions. 4163 init_gc_alloc_regions(evacuation_info); 4164 4165 // Actually do the work... 4166 evacuate_collection_set(evacuation_info); 4167 4168 // We do this to mainly verify the per-thread SATB buffers 4169 // (which have been filtered by now) since we didn't verify 4170 // them earlier. No point in re-checking the stacks / enqueued 4171 // buffers given that the CSet has not changed since last time 4172 // we checked. 4173 _cm->verify_no_cset_oops(false /* verify_stacks */, 4174 false /* verify_enqueued_buffers */, 4175 true /* verify_thread_buffers */, 4176 true /* verify_fingers */); 4177 4178 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4179 4180 eagerly_reclaim_humongous_regions(); 4181 4182 g1_policy()->clear_collection_set(); 4183 4184 cleanup_surviving_young_words(); 4185 4186 // Start a new incremental collection set for the next pause. 4187 g1_policy()->start_incremental_cset_building(); 4188 4189 clear_cset_fast_test(); 4190 4191 _young_list->reset_sampled_info(); 4192 4193 // Don't check the whole heap at this point as the 4194 // GC alloc regions from this pause have been tagged 4195 // as survivors and moved on to the survivor list. 4196 // Survivor regions will fail the !is_young() check. 4197 assert(check_young_list_empty(false /* check_heap */), 4198 "young list should be empty"); 4199 4200 #if YOUNG_LIST_VERBOSE 4201 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4202 _young_list->print(); 4203 #endif // YOUNG_LIST_VERBOSE 4204 4205 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4206 _young_list->first_survivor_region(), 4207 _young_list->last_survivor_region()); 4208 4209 _young_list->reset_auxilary_lists(); 4210 4211 if (evacuation_failed()) { 4212 _summary_bytes_used = recalculate_used(); 4213 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4214 for (uint i = 0; i < n_queues; i++) { 4215 if (_evacuation_failed_info_array[i].has_failed()) { 4216 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4217 } 4218 } 4219 } else { 4220 // The "used" of the the collection set have already been subtracted 4221 // when they were freed. Add in the bytes evacuated. 4222 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4223 } 4224 4225 if (g1_policy()->during_initial_mark_pause()) { 4226 // We have to do this before we notify the CM threads that 4227 // they can start working to make sure that all the 4228 // appropriate initialization is done on the CM object. 4229 concurrent_mark()->checkpointRootsInitialPost(); 4230 set_marking_started(); 4231 // Note that we don't actually trigger the CM thread at 4232 // this point. We do that later when we're sure that 4233 // the current thread has completed its logging output. 4234 } 4235 4236 allocate_dummy_regions(); 4237 4238 #if YOUNG_LIST_VERBOSE 4239 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4240 _young_list->print(); 4241 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4242 #endif // YOUNG_LIST_VERBOSE 4243 4244 init_mutator_alloc_region(); 4245 4246 { 4247 size_t expand_bytes = g1_policy()->expansion_amount(); 4248 if (expand_bytes > 0) { 4249 size_t bytes_before = capacity(); 4250 // No need for an ergo verbose message here, 4251 // expansion_amount() does this when it returns a value > 0. 4252 if (!expand(expand_bytes)) { 4253 // We failed to expand the heap so let's verify that 4254 // committed/uncommitted amount match the backing store 4255 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4256 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4257 } 4258 } 4259 } 4260 4261 // We redo the verification but now wrt to the new CSet which 4262 // has just got initialized after the previous CSet was freed. 4263 _cm->verify_no_cset_oops(true /* verify_stacks */, 4264 true /* verify_enqueued_buffers */, 4265 true /* verify_thread_buffers */, 4266 true /* verify_fingers */); 4267 _cm->note_end_of_gc(); 4268 4269 // This timing is only used by the ergonomics to handle our pause target. 4270 // It is unclear why this should not include the full pause. We will 4271 // investigate this in CR 7178365. 4272 double sample_end_time_sec = os::elapsedTime(); 4273 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4274 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4275 4276 MemoryService::track_memory_usage(); 4277 4278 // In prepare_for_verify() below we'll need to scan the deferred 4279 // update buffers to bring the RSets up-to-date if 4280 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4281 // the update buffers we'll probably need to scan cards on the 4282 // regions we just allocated to (i.e., the GC alloc 4283 // regions). However, during the last GC we called 4284 // set_saved_mark() on all the GC alloc regions, so card 4285 // scanning might skip the [saved_mark_word()...top()] area of 4286 // those regions (i.e., the area we allocated objects into 4287 // during the last GC). But it shouldn't. Given that 4288 // saved_mark_word() is conditional on whether the GC time stamp 4289 // on the region is current or not, by incrementing the GC time 4290 // stamp here we invalidate all the GC time stamps on all the 4291 // regions and saved_mark_word() will simply return top() for 4292 // all the regions. This is a nicer way of ensuring this rather 4293 // than iterating over the regions and fixing them. In fact, the 4294 // GC time stamp increment here also ensures that 4295 // saved_mark_word() will return top() between pauses, i.e., 4296 // during concurrent refinement. So we don't need the 4297 // is_gc_active() check to decided which top to use when 4298 // scanning cards (see CR 7039627). 4299 increment_gc_time_stamp(); 4300 4301 verify_after_gc(); 4302 check_bitmaps("GC End"); 4303 4304 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4305 ref_processor_stw()->verify_no_references_recorded(); 4306 4307 // CM reference discovery will be re-enabled if necessary. 4308 } 4309 4310 // We should do this after we potentially expand the heap so 4311 // that all the COMMIT events are generated before the end GC 4312 // event, and after we retire the GC alloc regions so that all 4313 // RETIRE events are generated before the end GC event. 4314 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4315 4316 if (mark_in_progress()) { 4317 concurrent_mark()->update_g1_committed(); 4318 } 4319 4320 #ifdef TRACESPINNING 4321 ParallelTaskTerminator::print_termination_counts(); 4322 #endif 4323 4324 gc_epilogue(false); 4325 } 4326 4327 // Print the remainder of the GC log output. 4328 log_gc_footer(os::elapsedTime() - pause_start_sec); 4329 4330 // It is not yet to safe to tell the concurrent mark to 4331 // start as we have some optional output below. We don't want the 4332 // output from the concurrent mark thread interfering with this 4333 // logging output either. 4334 4335 _hrs.verify_optional(); 4336 verify_region_sets_optional(); 4337 4338 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4339 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4340 4341 print_heap_after_gc(); 4342 trace_heap_after_gc(_gc_tracer_stw); 4343 4344 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4345 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4346 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4347 // before any GC notifications are raised. 4348 g1mm()->update_sizes(); 4349 4350 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4351 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4352 _gc_timer_stw->register_gc_end(); 4353 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4354 } 4355 // It should now be safe to tell the concurrent mark thread to start 4356 // without its logging output interfering with the logging output 4357 // that came from the pause. 4358 4359 if (should_start_conc_mark) { 4360 // CAUTION: after the doConcurrentMark() call below, 4361 // the concurrent marking thread(s) could be running 4362 // concurrently with us. Make sure that anything after 4363 // this point does not assume that we are the only GC thread 4364 // running. Note: of course, the actual marking work will 4365 // not start until the safepoint itself is released in 4366 // SuspendibleThreadSet::desynchronize(). 4367 doConcurrentMark(); 4368 } 4369 4370 return true; 4371 } 4372 4373 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4374 { 4375 size_t gclab_word_size; 4376 switch (purpose) { 4377 case GCAllocForSurvived: 4378 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4379 break; 4380 case GCAllocForTenured: 4381 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4382 break; 4383 default: 4384 assert(false, "unknown GCAllocPurpose"); 4385 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4386 break; 4387 } 4388 4389 // Prevent humongous PLAB sizes for two reasons: 4390 // * PLABs are allocated using a similar paths as oops, but should 4391 // never be in a humongous region 4392 // * Allowing humongous PLABs needlessly churns the region free lists 4393 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4394 } 4395 4396 void G1CollectedHeap::init_mutator_alloc_region() { 4397 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4398 _mutator_alloc_region.init(); 4399 } 4400 4401 void G1CollectedHeap::release_mutator_alloc_region() { 4402 _mutator_alloc_region.release(); 4403 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4404 } 4405 4406 void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) { 4407 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4408 _retained_old_gc_alloc_region = NULL; 4409 4410 // We will discard the current GC alloc region if: 4411 // a) it's in the collection set (it can happen!), 4412 // b) it's already full (no point in using it), 4413 // c) it's empty (this means that it was emptied during 4414 // a cleanup and it should be on the free list now), or 4415 // d) it's humongous (this means that it was emptied 4416 // during a cleanup and was added to the free list, but 4417 // has been subsequently used to allocate a humongous 4418 // object that may be less than the region size). 4419 if (retained_region != NULL && 4420 !retained_region->in_collection_set() && 4421 !(retained_region->top() == retained_region->end()) && 4422 !retained_region->is_empty() && 4423 !retained_region->isHumongous()) { 4424 retained_region->record_top_and_timestamp(); 4425 // The retained region was added to the old region set when it was 4426 // retired. We have to remove it now, since we don't allow regions 4427 // we allocate to in the region sets. We'll re-add it later, when 4428 // it's retired again. 4429 _old_set.remove(retained_region); 4430 bool during_im = g1_policy()->during_initial_mark_pause(); 4431 retained_region->note_start_of_copying(during_im); 4432 _old_gc_alloc_region.set(retained_region); 4433 _hr_printer.reuse(retained_region); 4434 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4435 } 4436 } 4437 4438 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4439 assert_at_safepoint(true /* should_be_vm_thread */); 4440 4441 _survivor_gc_alloc_region.init(); 4442 _old_gc_alloc_region.init(); 4443 4444 use_retained_old_gc_alloc_region(evacuation_info); 4445 } 4446 4447 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4448 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4449 _old_gc_alloc_region.count()); 4450 _survivor_gc_alloc_region.release(); 4451 // If we have an old GC alloc region to release, we'll save it in 4452 // _retained_old_gc_alloc_region. If we don't 4453 // _retained_old_gc_alloc_region will become NULL. This is what we 4454 // want either way so no reason to check explicitly for either 4455 // condition. 4456 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4457 4458 if (ResizePLAB) { 4459 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4460 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4461 } 4462 } 4463 4464 void G1CollectedHeap::abandon_gc_alloc_regions() { 4465 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4466 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4467 _retained_old_gc_alloc_region = NULL; 4468 } 4469 4470 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4471 _drain_in_progress = false; 4472 set_evac_failure_closure(cl); 4473 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4474 } 4475 4476 void G1CollectedHeap::finalize_for_evac_failure() { 4477 assert(_evac_failure_scan_stack != NULL && 4478 _evac_failure_scan_stack->length() == 0, 4479 "Postcondition"); 4480 assert(!_drain_in_progress, "Postcondition"); 4481 delete _evac_failure_scan_stack; 4482 _evac_failure_scan_stack = NULL; 4483 } 4484 4485 void G1CollectedHeap::remove_self_forwarding_pointers() { 4486 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4487 4488 double remove_self_forwards_start = os::elapsedTime(); 4489 4490 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4491 4492 if (G1CollectedHeap::use_parallel_gc_threads()) { 4493 set_par_threads(); 4494 workers()->run_task(&rsfp_task); 4495 set_par_threads(0); 4496 } else { 4497 rsfp_task.work(0); 4498 } 4499 4500 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4501 4502 // Reset the claim values in the regions in the collection set. 4503 reset_cset_heap_region_claim_values(); 4504 4505 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4506 4507 // Now restore saved marks, if any. 4508 assert(_objs_with_preserved_marks.size() == 4509 _preserved_marks_of_objs.size(), "Both or none."); 4510 while (!_objs_with_preserved_marks.is_empty()) { 4511 oop obj = _objs_with_preserved_marks.pop(); 4512 markOop m = _preserved_marks_of_objs.pop(); 4513 obj->set_mark(m); 4514 } 4515 _objs_with_preserved_marks.clear(true); 4516 _preserved_marks_of_objs.clear(true); 4517 4518 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4519 } 4520 4521 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4522 _evac_failure_scan_stack->push(obj); 4523 } 4524 4525 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4526 assert(_evac_failure_scan_stack != NULL, "precondition"); 4527 4528 while (_evac_failure_scan_stack->length() > 0) { 4529 oop obj = _evac_failure_scan_stack->pop(); 4530 _evac_failure_closure->set_region(heap_region_containing(obj)); 4531 obj->oop_iterate_backwards<false>(_evac_failure_closure); 4532 } 4533 } 4534 4535 oop 4536 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4537 oop old) { 4538 assert(obj_in_cs(old), 4539 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4540 (HeapWord*) old)); 4541 markOop m = old->mark(); 4542 oop forward_ptr = old->forward_to_atomic(old); 4543 if (forward_ptr == NULL) { 4544 // Forward-to-self succeeded. 4545 assert(_par_scan_state != NULL, "par scan state"); 4546 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4547 uint queue_num = _par_scan_state->queue_num(); 4548 4549 _evacuation_failed = true; 4550 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4551 if (_evac_failure_closure != cl) { 4552 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4553 assert(!_drain_in_progress, 4554 "Should only be true while someone holds the lock."); 4555 // Set the global evac-failure closure to the current thread's. 4556 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4557 set_evac_failure_closure(cl); 4558 // Now do the common part. 4559 handle_evacuation_failure_common(old, m); 4560 // Reset to NULL. 4561 set_evac_failure_closure(NULL); 4562 } else { 4563 // The lock is already held, and this is recursive. 4564 assert(_drain_in_progress, "This should only be the recursive case."); 4565 handle_evacuation_failure_common(old, m); 4566 } 4567 return old; 4568 } else { 4569 // Forward-to-self failed. Either someone else managed to allocate 4570 // space for this object (old != forward_ptr) or they beat us in 4571 // self-forwarding it (old == forward_ptr). 4572 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4573 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4574 "should not be in the CSet", 4575 (HeapWord*) old, (HeapWord*) forward_ptr)); 4576 return forward_ptr; 4577 } 4578 } 4579 4580 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4581 preserve_mark_if_necessary(old, m); 4582 4583 HeapRegion* r = heap_region_containing(old); 4584 if (!r->evacuation_failed()) { 4585 r->set_evacuation_failed(true); 4586 _hr_printer.evac_failure(r); 4587 } 4588 4589 push_on_evac_failure_scan_stack(old); 4590 4591 if (!_drain_in_progress) { 4592 // prevent recursion in copy_to_survivor_space() 4593 _drain_in_progress = true; 4594 drain_evac_failure_scan_stack(); 4595 _drain_in_progress = false; 4596 } 4597 } 4598 4599 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4600 assert(evacuation_failed(), "Oversaving!"); 4601 // We want to call the "for_promotion_failure" version only in the 4602 // case of a promotion failure. 4603 if (m->must_be_preserved_for_promotion_failure(obj)) { 4604 _objs_with_preserved_marks.push(obj); 4605 _preserved_marks_of_objs.push(m); 4606 } 4607 } 4608 4609 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4610 size_t word_size) { 4611 if (purpose == GCAllocForSurvived) { 4612 HeapWord* result = survivor_attempt_allocation(word_size); 4613 if (result != NULL) { 4614 return result; 4615 } else { 4616 // Let's try to allocate in the old gen in case we can fit the 4617 // object there. 4618 return old_attempt_allocation(word_size); 4619 } 4620 } else { 4621 assert(purpose == GCAllocForTenured, "sanity"); 4622 HeapWord* result = old_attempt_allocation(word_size); 4623 if (result != NULL) { 4624 return result; 4625 } else { 4626 // Let's try to allocate in the survivors in case we can fit the 4627 // object there. 4628 return survivor_attempt_allocation(word_size); 4629 } 4630 } 4631 4632 ShouldNotReachHere(); 4633 // Trying to keep some compilers happy. 4634 return NULL; 4635 } 4636 4637 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4638 ParGCAllocBuffer(gclab_word_size), _retired(true) { } 4639 4640 void G1ParCopyHelper::mark_object(oop obj) { 4641 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4642 4643 // We know that the object is not moving so it's safe to read its size. 4644 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4645 } 4646 4647 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4648 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4649 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4650 assert(from_obj != to_obj, "should not be self-forwarded"); 4651 4652 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4653 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4654 4655 // The object might be in the process of being copied by another 4656 // worker so we cannot trust that its to-space image is 4657 // well-formed. So we have to read its size from its from-space 4658 // image which we know should not be changing. 4659 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4660 } 4661 4662 template <class T> 4663 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4664 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4665 _scanned_klass->record_modified_oops(); 4666 } 4667 } 4668 4669 template <G1Barrier barrier, G1Mark do_mark_object> 4670 template <class T> 4671 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4672 T heap_oop = oopDesc::load_heap_oop(p); 4673 4674 if (oopDesc::is_null(heap_oop)) { 4675 return; 4676 } 4677 4678 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4679 4680 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4681 4682 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj); 4683 4684 if (state == G1CollectedHeap::InCSet) { 4685 oop forwardee; 4686 if (obj->is_forwarded()) { 4687 forwardee = obj->forwardee(); 4688 } else { 4689 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4690 } 4691 assert(forwardee != NULL, "forwardee should not be NULL"); 4692 oopDesc::encode_store_heap_oop(p, forwardee); 4693 if (do_mark_object != G1MarkNone && forwardee != obj) { 4694 // If the object is self-forwarded we don't need to explicitly 4695 // mark it, the evacuation failure protocol will do so. 4696 mark_forwarded_object(obj, forwardee); 4697 } 4698 4699 if (barrier == G1BarrierKlass) { 4700 do_klass_barrier(p, forwardee); 4701 } 4702 } else { 4703 if (state == G1CollectedHeap::IsHumongous) { 4704 _g1->set_humongous_is_live(obj); 4705 } 4706 // The object is not in collection set. If we're a root scanning 4707 // closure during an initial mark pause then attempt to mark the object. 4708 if (do_mark_object == G1MarkFromRoot) { 4709 mark_object(obj); 4710 } 4711 } 4712 4713 if (barrier == G1BarrierEvac) { 4714 _par_scan_state->update_rs(_from, p, _worker_id); 4715 } 4716 } 4717 4718 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4719 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4720 4721 class G1ParEvacuateFollowersClosure : public VoidClosure { 4722 protected: 4723 G1CollectedHeap* _g1h; 4724 G1ParScanThreadState* _par_scan_state; 4725 RefToScanQueueSet* _queues; 4726 ParallelTaskTerminator* _terminator; 4727 4728 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4729 RefToScanQueueSet* queues() { return _queues; } 4730 ParallelTaskTerminator* terminator() { return _terminator; } 4731 4732 public: 4733 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4734 G1ParScanThreadState* par_scan_state, 4735 RefToScanQueueSet* queues, 4736 ParallelTaskTerminator* terminator) 4737 : _g1h(g1h), _par_scan_state(par_scan_state), 4738 _queues(queues), _terminator(terminator) {} 4739 4740 void do_void(); 4741 4742 private: 4743 inline bool offer_termination(); 4744 }; 4745 4746 bool G1ParEvacuateFollowersClosure::offer_termination() { 4747 G1ParScanThreadState* const pss = par_scan_state(); 4748 pss->start_term_time(); 4749 const bool res = terminator()->offer_termination(); 4750 pss->end_term_time(); 4751 return res; 4752 } 4753 4754 void G1ParEvacuateFollowersClosure::do_void() { 4755 G1ParScanThreadState* const pss = par_scan_state(); 4756 pss->trim_queue(); 4757 do { 4758 pss->steal_and_trim_queue(queues()); 4759 } while (!offer_termination()); 4760 } 4761 4762 class G1KlassScanClosure : public KlassClosure { 4763 G1ParCopyHelper* _closure; 4764 bool _process_only_dirty; 4765 int _count; 4766 public: 4767 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4768 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4769 void do_klass(Klass* klass) { 4770 // If the klass has not been dirtied we know that there's 4771 // no references into the young gen and we can skip it. 4772 if (!_process_only_dirty || klass->has_modified_oops()) { 4773 // Clean the klass since we're going to scavenge all the metadata. 4774 klass->clear_modified_oops(); 4775 4776 // Tell the closure that this klass is the Klass to scavenge 4777 // and is the one to dirty if oops are left pointing into the young gen. 4778 _closure->set_scanned_klass(klass); 4779 4780 klass->oops_do(_closure); 4781 4782 _closure->set_scanned_klass(NULL); 4783 } 4784 _count++; 4785 } 4786 }; 4787 4788 class G1ParTask : public AbstractGangTask { 4789 protected: 4790 G1CollectedHeap* _g1h; 4791 RefToScanQueueSet *_queues; 4792 ParallelTaskTerminator _terminator; 4793 uint _n_workers; 4794 4795 Mutex _stats_lock; 4796 Mutex* stats_lock() { return &_stats_lock; } 4797 4798 size_t getNCards() { 4799 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4800 / G1BlockOffsetSharedArray::N_bytes; 4801 } 4802 4803 public: 4804 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4805 : AbstractGangTask("G1 collection"), 4806 _g1h(g1h), 4807 _queues(task_queues), 4808 _terminator(0, _queues), 4809 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4810 {} 4811 4812 RefToScanQueueSet* queues() { return _queues; } 4813 4814 RefToScanQueue *work_queue(int i) { 4815 return queues()->queue(i); 4816 } 4817 4818 ParallelTaskTerminator* terminator() { return &_terminator; } 4819 4820 virtual void set_for_termination(int active_workers) { 4821 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4822 // in the young space (_par_seq_tasks) in the G1 heap 4823 // for SequentialSubTasksDone. 4824 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4825 // both of which need setting by set_n_termination(). 4826 _g1h->SharedHeap::set_n_termination(active_workers); 4827 _g1h->set_n_termination(active_workers); 4828 terminator()->reset_for_reuse(active_workers); 4829 _n_workers = active_workers; 4830 } 4831 4832 // Helps out with CLD processing. 4833 // 4834 // During InitialMark we need to: 4835 // 1) Scavenge all CLDs for the young GC. 4836 // 2) Mark all objects directly reachable from strong CLDs. 4837 template <G1Mark do_mark_object> 4838 class G1CLDClosure : public CLDClosure { 4839 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4840 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4841 G1KlassScanClosure _klass_in_cld_closure; 4842 bool _claim; 4843 4844 public: 4845 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4846 bool only_young, bool claim) 4847 : _oop_closure(oop_closure), 4848 _oop_in_klass_closure(oop_closure->g1(), 4849 oop_closure->pss(), 4850 oop_closure->rp()), 4851 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4852 _claim(claim) { 4853 4854 } 4855 4856 void do_cld(ClassLoaderData* cld) { 4857 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4858 } 4859 }; 4860 4861 class G1CodeBlobClosure: public CodeBlobClosure { 4862 OopClosure* _f; 4863 4864 public: 4865 G1CodeBlobClosure(OopClosure* f) : _f(f) {} 4866 void do_code_blob(CodeBlob* blob) { 4867 nmethod* that = blob->as_nmethod_or_null(); 4868 if (that != NULL) { 4869 if (!that->test_set_oops_do_mark()) { 4870 that->oops_do(_f); 4871 that->fix_oop_relocations(); 4872 } 4873 } 4874 } 4875 }; 4876 4877 void work(uint worker_id) { 4878 if (worker_id >= _n_workers) return; // no work needed this round 4879 4880 double start_time_ms = os::elapsedTime() * 1000.0; 4881 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4882 4883 { 4884 ResourceMark rm; 4885 HandleMark hm; 4886 4887 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4888 4889 G1ParScanThreadState pss(_g1h, worker_id, rp); 4890 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4891 4892 pss.set_evac_failure_closure(&evac_failure_cl); 4893 4894 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4895 4896 // Non-IM young GC. 4897 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4898 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4899 only_young, // Only process dirty klasses. 4900 false); // No need to claim CLDs. 4901 // IM young GC. 4902 // Strong roots closures. 4903 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4904 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4905 false, // Process all klasses. 4906 true); // Need to claim CLDs. 4907 // Weak roots closures. 4908 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4909 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4910 false, // Process all klasses. 4911 true); // Need to claim CLDs. 4912 4913 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl); 4914 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl); 4915 // IM Weak code roots are handled later. 4916 4917 OopClosure* strong_root_cl; 4918 OopClosure* weak_root_cl; 4919 CLDClosure* strong_cld_cl; 4920 CLDClosure* weak_cld_cl; 4921 CodeBlobClosure* strong_code_cl; 4922 4923 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4924 // We also need to mark copied objects. 4925 strong_root_cl = &scan_mark_root_cl; 4926 weak_root_cl = &scan_mark_weak_root_cl; 4927 strong_cld_cl = &scan_mark_cld_cl; 4928 weak_cld_cl = &scan_mark_weak_cld_cl; 4929 strong_code_cl = &scan_mark_code_cl; 4930 } else { 4931 strong_root_cl = &scan_only_root_cl; 4932 weak_root_cl = &scan_only_root_cl; 4933 strong_cld_cl = &scan_only_cld_cl; 4934 weak_cld_cl = &scan_only_cld_cl; 4935 strong_code_cl = &scan_only_code_cl; 4936 } 4937 4938 4939 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4940 4941 pss.start_strong_roots(); 4942 _g1h->g1_process_roots(strong_root_cl, 4943 weak_root_cl, 4944 &push_heap_rs_cl, 4945 strong_cld_cl, 4946 weak_cld_cl, 4947 strong_code_cl, 4948 worker_id); 4949 4950 pss.end_strong_roots(); 4951 4952 { 4953 double start = os::elapsedTime(); 4954 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4955 evac.do_void(); 4956 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4957 double term_ms = pss.term_time()*1000.0; 4958 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4959 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4960 } 4961 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4962 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4963 4964 if (ParallelGCVerbose) { 4965 MutexLocker x(stats_lock()); 4966 pss.print_termination_stats(worker_id); 4967 } 4968 4969 assert(pss.queue_is_empty(), "should be empty"); 4970 4971 // Close the inner scope so that the ResourceMark and HandleMark 4972 // destructors are executed here and are included as part of the 4973 // "GC Worker Time". 4974 } 4975 4976 double end_time_ms = os::elapsedTime() * 1000.0; 4977 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4978 } 4979 }; 4980 4981 // *** Common G1 Evacuation Stuff 4982 4983 // This method is run in a GC worker. 4984 4985 void 4986 G1CollectedHeap:: 4987 g1_process_roots(OopClosure* scan_non_heap_roots, 4988 OopClosure* scan_non_heap_weak_roots, 4989 OopsInHeapRegionClosure* scan_rs, 4990 CLDClosure* scan_strong_clds, 4991 CLDClosure* scan_weak_clds, 4992 CodeBlobClosure* scan_strong_code, 4993 uint worker_i) { 4994 4995 // First scan the shared roots. 4996 double ext_roots_start = os::elapsedTime(); 4997 double closure_app_time_sec = 0.0; 4998 4999 bool during_im = _g1h->g1_policy()->during_initial_mark_pause(); 5000 5001 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5002 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 5003 5004 process_roots(false, // no scoping; this is parallel code 5005 SharedHeap::SO_None, 5006 &buf_scan_non_heap_roots, 5007 &buf_scan_non_heap_weak_roots, 5008 scan_strong_clds, 5009 // Initial Mark handles the weak CLDs separately. 5010 (during_im ? NULL : scan_weak_clds), 5011 scan_strong_code); 5012 5013 // Now the CM ref_processor roots. 5014 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5015 // We need to treat the discovered reference lists of the 5016 // concurrent mark ref processor as roots and keep entries 5017 // (which are added by the marking threads) on them live 5018 // until they can be processed at the end of marking. 5019 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5020 } 5021 5022 if (during_im) { 5023 // Barrier to make sure all workers passed 5024 // the strong CLD and strong nmethods phases. 5025 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads()); 5026 5027 // Now take the complement of the strong CLDs. 5028 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 5029 } 5030 5031 // Finish up any enqueued closure apps (attributed as object copy time). 5032 buf_scan_non_heap_roots.done(); 5033 buf_scan_non_heap_weak_roots.done(); 5034 5035 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 5036 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 5037 5038 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5039 5040 double ext_root_time_ms = 5041 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5042 5043 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5044 5045 // During conc marking we have to filter the per-thread SATB buffers 5046 // to make sure we remove any oops into the CSet (which will show up 5047 // as implicitly live). 5048 double satb_filtering_ms = 0.0; 5049 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5050 if (mark_in_progress()) { 5051 double satb_filter_start = os::elapsedTime(); 5052 5053 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5054 5055 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5056 } 5057 } 5058 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5059 5060 // Now scan the complement of the collection set. 5061 MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations); 5062 5063 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 5064 5065 _process_strong_tasks->all_tasks_completed(); 5066 } 5067 5068 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 5069 private: 5070 BoolObjectClosure* _is_alive; 5071 int _initial_string_table_size; 5072 int _initial_symbol_table_size; 5073 5074 bool _process_strings; 5075 int _strings_processed; 5076 int _strings_removed; 5077 5078 bool _process_symbols; 5079 int _symbols_processed; 5080 int _symbols_removed; 5081 5082 bool _do_in_parallel; 5083 public: 5084 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 5085 AbstractGangTask("String/Symbol Unlinking"), 5086 _is_alive(is_alive), 5087 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 5088 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 5089 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 5090 5091 _initial_string_table_size = StringTable::the_table()->table_size(); 5092 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 5093 if (process_strings) { 5094 StringTable::clear_parallel_claimed_index(); 5095 } 5096 if (process_symbols) { 5097 SymbolTable::clear_parallel_claimed_index(); 5098 } 5099 } 5100 5101 ~G1StringSymbolTableUnlinkTask() { 5102 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 5103 err_msg("claim value %d after unlink less than initial string table size %d", 5104 StringTable::parallel_claimed_index(), _initial_string_table_size)); 5105 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 5106 err_msg("claim value %d after unlink less than initial symbol table size %d", 5107 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 5108 5109 if (G1TraceStringSymbolTableScrubbing) { 5110 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5111 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5112 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5113 strings_processed(), strings_removed(), 5114 symbols_processed(), symbols_removed()); 5115 } 5116 } 5117 5118 void work(uint worker_id) { 5119 if (_do_in_parallel) { 5120 int strings_processed = 0; 5121 int strings_removed = 0; 5122 int symbols_processed = 0; 5123 int symbols_removed = 0; 5124 if (_process_strings) { 5125 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5126 Atomic::add(strings_processed, &_strings_processed); 5127 Atomic::add(strings_removed, &_strings_removed); 5128 } 5129 if (_process_symbols) { 5130 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5131 Atomic::add(symbols_processed, &_symbols_processed); 5132 Atomic::add(symbols_removed, &_symbols_removed); 5133 } 5134 } else { 5135 if (_process_strings) { 5136 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5137 } 5138 if (_process_symbols) { 5139 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5140 } 5141 } 5142 } 5143 5144 size_t strings_processed() const { return (size_t)_strings_processed; } 5145 size_t strings_removed() const { return (size_t)_strings_removed; } 5146 5147 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5148 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5149 }; 5150 5151 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 5152 private: 5153 static Monitor* _lock; 5154 5155 BoolObjectClosure* const _is_alive; 5156 const bool _unloading_occurred; 5157 const uint _num_workers; 5158 5159 // Variables used to claim nmethods. 5160 nmethod* _first_nmethod; 5161 volatile nmethod* _claimed_nmethod; 5162 5163 // The list of nmethods that need to be processed by the second pass. 5164 volatile nmethod* _postponed_list; 5165 volatile uint _num_entered_barrier; 5166 5167 public: 5168 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 5169 _is_alive(is_alive), 5170 _unloading_occurred(unloading_occurred), 5171 _num_workers(num_workers), 5172 _first_nmethod(NULL), 5173 _claimed_nmethod(NULL), 5174 _postponed_list(NULL), 5175 _num_entered_barrier(0) 5176 { 5177 nmethod::increase_unloading_clock(); 5178 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first()); 5179 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 5180 } 5181 5182 ~G1CodeCacheUnloadingTask() { 5183 CodeCache::verify_clean_inline_caches(); 5184 5185 CodeCache::set_needs_cache_clean(false); 5186 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 5187 5188 CodeCache::verify_icholder_relocations(); 5189 } 5190 5191 private: 5192 void add_to_postponed_list(nmethod* nm) { 5193 nmethod* old; 5194 do { 5195 old = (nmethod*)_postponed_list; 5196 nm->set_unloading_next(old); 5197 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 5198 } 5199 5200 void clean_nmethod(nmethod* nm) { 5201 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 5202 5203 if (postponed) { 5204 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 5205 add_to_postponed_list(nm); 5206 } 5207 5208 // Mark that this thread has been cleaned/unloaded. 5209 // After this call, it will be safe to ask if this nmethod was unloaded or not. 5210 nm->set_unloading_clock(nmethod::global_unloading_clock()); 5211 } 5212 5213 void clean_nmethod_postponed(nmethod* nm) { 5214 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 5215 } 5216 5217 static const int MaxClaimNmethods = 16; 5218 5219 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 5220 nmethod* first; 5221 nmethod* last; 5222 5223 do { 5224 *num_claimed_nmethods = 0; 5225 5226 first = last = (nmethod*)_claimed_nmethod; 5227 5228 if (first != NULL) { 5229 for (int i = 0; i < MaxClaimNmethods; i++) { 5230 last = CodeCache::alive_nmethod(CodeCache::next(last)); 5231 5232 if (last == NULL) { 5233 break; 5234 } 5235 5236 claimed_nmethods[i] = last; 5237 (*num_claimed_nmethods)++; 5238 } 5239 } 5240 5241 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first); 5242 } 5243 5244 nmethod* claim_postponed_nmethod() { 5245 nmethod* claim; 5246 nmethod* next; 5247 5248 do { 5249 claim = (nmethod*)_postponed_list; 5250 if (claim == NULL) { 5251 return NULL; 5252 } 5253 5254 next = claim->unloading_next(); 5255 5256 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 5257 5258 return claim; 5259 } 5260 5261 public: 5262 // Mark that we're done with the first pass of nmethod cleaning. 5263 void barrier_mark(uint worker_id) { 5264 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5265 _num_entered_barrier++; 5266 if (_num_entered_barrier == _num_workers) { 5267 ml.notify_all(); 5268 } 5269 } 5270 5271 // See if we have to wait for the other workers to 5272 // finish their first-pass nmethod cleaning work. 5273 void barrier_wait(uint worker_id) { 5274 if (_num_entered_barrier < _num_workers) { 5275 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5276 while (_num_entered_barrier < _num_workers) { 5277 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 5278 } 5279 } 5280 } 5281 5282 // Cleaning and unloading of nmethods. Some work has to be postponed 5283 // to the second pass, when we know which nmethods survive. 5284 void work_first_pass(uint worker_id) { 5285 // The first nmethods is claimed by the first worker. 5286 if (worker_id == 0 && _first_nmethod != NULL) { 5287 clean_nmethod(_first_nmethod); 5288 _first_nmethod = NULL; 5289 } 5290 5291 int num_claimed_nmethods; 5292 nmethod* claimed_nmethods[MaxClaimNmethods]; 5293 5294 while (true) { 5295 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 5296 5297 if (num_claimed_nmethods == 0) { 5298 break; 5299 } 5300 5301 for (int i = 0; i < num_claimed_nmethods; i++) { 5302 clean_nmethod(claimed_nmethods[i]); 5303 } 5304 } 5305 } 5306 5307 void work_second_pass(uint worker_id) { 5308 nmethod* nm; 5309 // Take care of postponed nmethods. 5310 while ((nm = claim_postponed_nmethod()) != NULL) { 5311 clean_nmethod_postponed(nm); 5312 } 5313 } 5314 }; 5315 5316 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock"); 5317 5318 class G1KlassCleaningTask : public StackObj { 5319 BoolObjectClosure* _is_alive; 5320 volatile jint _clean_klass_tree_claimed; 5321 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 5322 5323 public: 5324 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 5325 _is_alive(is_alive), 5326 _clean_klass_tree_claimed(0), 5327 _klass_iterator() { 5328 } 5329 5330 private: 5331 bool claim_clean_klass_tree_task() { 5332 if (_clean_klass_tree_claimed) { 5333 return false; 5334 } 5335 5336 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 5337 } 5338 5339 InstanceKlass* claim_next_klass() { 5340 Klass* klass; 5341 do { 5342 klass =_klass_iterator.next_klass(); 5343 } while (klass != NULL && !klass->oop_is_instance()); 5344 5345 return (InstanceKlass*)klass; 5346 } 5347 5348 public: 5349 5350 void clean_klass(InstanceKlass* ik) { 5351 ik->clean_implementors_list(_is_alive); 5352 ik->clean_method_data(_is_alive); 5353 5354 // G1 specific cleanup work that has 5355 // been moved here to be done in parallel. 5356 ik->clean_dependent_nmethods(); 5357 } 5358 5359 void work() { 5360 ResourceMark rm; 5361 5362 // One worker will clean the subklass/sibling klass tree. 5363 if (claim_clean_klass_tree_task()) { 5364 Klass::clean_subklass_tree(_is_alive); 5365 } 5366 5367 // All workers will help cleaning the classes, 5368 InstanceKlass* klass; 5369 while ((klass = claim_next_klass()) != NULL) { 5370 clean_klass(klass); 5371 } 5372 } 5373 }; 5374 5375 // To minimize the remark pause times, the tasks below are done in parallel. 5376 class G1ParallelCleaningTask : public AbstractGangTask { 5377 private: 5378 G1StringSymbolTableUnlinkTask _string_symbol_task; 5379 G1CodeCacheUnloadingTask _code_cache_task; 5380 G1KlassCleaningTask _klass_cleaning_task; 5381 5382 public: 5383 // The constructor is run in the VMThread. 5384 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 5385 AbstractGangTask("Parallel Cleaning"), 5386 _string_symbol_task(is_alive, process_strings, process_symbols), 5387 _code_cache_task(num_workers, is_alive, unloading_occurred), 5388 _klass_cleaning_task(is_alive) { 5389 } 5390 5391 // The parallel work done by all worker threads. 5392 void work(uint worker_id) { 5393 // Do first pass of code cache cleaning. 5394 _code_cache_task.work_first_pass(worker_id); 5395 5396 // Let the threads mark that the first pass is done. 5397 _code_cache_task.barrier_mark(worker_id); 5398 5399 // Clean the Strings and Symbols. 5400 _string_symbol_task.work(worker_id); 5401 5402 // Wait for all workers to finish the first code cache cleaning pass. 5403 _code_cache_task.barrier_wait(worker_id); 5404 5405 // Do the second code cache cleaning work, which realize on 5406 // the liveness information gathered during the first pass. 5407 _code_cache_task.work_second_pass(worker_id); 5408 5409 // Clean all klasses that were not unloaded. 5410 _klass_cleaning_task.work(); 5411 } 5412 }; 5413 5414 5415 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5416 bool process_strings, 5417 bool process_symbols, 5418 bool class_unloading_occurred) { 5419 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5420 workers()->active_workers() : 1); 5421 5422 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5423 n_workers, class_unloading_occurred); 5424 if (G1CollectedHeap::use_parallel_gc_threads()) { 5425 set_par_threads(n_workers); 5426 workers()->run_task(&g1_unlink_task); 5427 set_par_threads(0); 5428 } else { 5429 g1_unlink_task.work(0); 5430 } 5431 } 5432 5433 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5434 bool process_strings, bool process_symbols) { 5435 { 5436 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5437 _g1h->workers()->active_workers() : 1); 5438 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5439 if (G1CollectedHeap::use_parallel_gc_threads()) { 5440 set_par_threads(n_workers); 5441 workers()->run_task(&g1_unlink_task); 5442 set_par_threads(0); 5443 } else { 5444 g1_unlink_task.work(0); 5445 } 5446 } 5447 5448 if (G1StringDedup::is_enabled()) { 5449 G1StringDedup::unlink(is_alive); 5450 } 5451 } 5452 5453 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5454 private: 5455 DirtyCardQueueSet* _queue; 5456 public: 5457 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5458 5459 virtual void work(uint worker_id) { 5460 double start_time = os::elapsedTime(); 5461 5462 RedirtyLoggedCardTableEntryClosure cl; 5463 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5464 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5465 } else { 5466 _queue->apply_closure_to_all_completed_buffers(&cl); 5467 } 5468 5469 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5470 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5471 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5472 } 5473 }; 5474 5475 void G1CollectedHeap::redirty_logged_cards() { 5476 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates."); 5477 double redirty_logged_cards_start = os::elapsedTime(); 5478 5479 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5480 _g1h->workers()->active_workers() : 1); 5481 5482 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5483 dirty_card_queue_set().reset_for_par_iteration(); 5484 if (use_parallel_gc_threads()) { 5485 set_par_threads(n_workers); 5486 workers()->run_task(&redirty_task); 5487 set_par_threads(0); 5488 } else { 5489 redirty_task.work(0); 5490 } 5491 5492 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5493 dcq.merge_bufferlists(&dirty_card_queue_set()); 5494 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5495 5496 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5497 } 5498 5499 // Weak Reference Processing support 5500 5501 // An always "is_alive" closure that is used to preserve referents. 5502 // If the object is non-null then it's alive. Used in the preservation 5503 // of referent objects that are pointed to by reference objects 5504 // discovered by the CM ref processor. 5505 class G1AlwaysAliveClosure: public BoolObjectClosure { 5506 G1CollectedHeap* _g1; 5507 public: 5508 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5509 bool do_object_b(oop p) { 5510 if (p != NULL) { 5511 return true; 5512 } 5513 return false; 5514 } 5515 }; 5516 5517 bool G1STWIsAliveClosure::do_object_b(oop p) { 5518 // An object is reachable if it is outside the collection set, 5519 // or is inside and copied. 5520 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5521 } 5522 5523 // Non Copying Keep Alive closure 5524 class G1KeepAliveClosure: public OopClosure { 5525 G1CollectedHeap* _g1; 5526 public: 5527 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5528 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5529 void do_oop(oop* p) { 5530 oop obj = *p; 5531 5532 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj); 5533 if (obj == NULL || cset_state == G1CollectedHeap::InNeither) { 5534 return; 5535 } 5536 if (cset_state == G1CollectedHeap::InCSet) { 5537 assert( obj->is_forwarded(), "invariant" ); 5538 *p = obj->forwardee(); 5539 } else { 5540 assert(!obj->is_forwarded(), "invariant" ); 5541 assert(cset_state == G1CollectedHeap::IsHumongous, 5542 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state)); 5543 _g1->set_humongous_is_live(obj); 5544 } 5545 } 5546 }; 5547 5548 // Copying Keep Alive closure - can be called from both 5549 // serial and parallel code as long as different worker 5550 // threads utilize different G1ParScanThreadState instances 5551 // and different queues. 5552 5553 class G1CopyingKeepAliveClosure: public OopClosure { 5554 G1CollectedHeap* _g1h; 5555 OopClosure* _copy_non_heap_obj_cl; 5556 G1ParScanThreadState* _par_scan_state; 5557 5558 public: 5559 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5560 OopClosure* non_heap_obj_cl, 5561 G1ParScanThreadState* pss): 5562 _g1h(g1h), 5563 _copy_non_heap_obj_cl(non_heap_obj_cl), 5564 _par_scan_state(pss) 5565 {} 5566 5567 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5568 virtual void do_oop( oop* p) { do_oop_work(p); } 5569 5570 template <class T> void do_oop_work(T* p) { 5571 oop obj = oopDesc::load_decode_heap_oop(p); 5572 5573 if (_g1h->is_in_cset_or_humongous(obj)) { 5574 // If the referent object has been forwarded (either copied 5575 // to a new location or to itself in the event of an 5576 // evacuation failure) then we need to update the reference 5577 // field and, if both reference and referent are in the G1 5578 // heap, update the RSet for the referent. 5579 // 5580 // If the referent has not been forwarded then we have to keep 5581 // it alive by policy. Therefore we have copy the referent. 5582 // 5583 // If the reference field is in the G1 heap then we can push 5584 // on the PSS queue. When the queue is drained (after each 5585 // phase of reference processing) the object and it's followers 5586 // will be copied, the reference field set to point to the 5587 // new location, and the RSet updated. Otherwise we need to 5588 // use the the non-heap or metadata closures directly to copy 5589 // the referent object and update the pointer, while avoiding 5590 // updating the RSet. 5591 5592 if (_g1h->is_in_g1_reserved(p)) { 5593 _par_scan_state->push_on_queue(p); 5594 } else { 5595 assert(!Metaspace::contains((const void*)p), 5596 err_msg("Unexpectedly found a pointer from metadata: " 5597 PTR_FORMAT, p)); 5598 _copy_non_heap_obj_cl->do_oop(p); 5599 } 5600 } 5601 } 5602 }; 5603 5604 // Serial drain queue closure. Called as the 'complete_gc' 5605 // closure for each discovered list in some of the 5606 // reference processing phases. 5607 5608 class G1STWDrainQueueClosure: public VoidClosure { 5609 protected: 5610 G1CollectedHeap* _g1h; 5611 G1ParScanThreadState* _par_scan_state; 5612 5613 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5614 5615 public: 5616 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5617 _g1h(g1h), 5618 _par_scan_state(pss) 5619 { } 5620 5621 void do_void() { 5622 G1ParScanThreadState* const pss = par_scan_state(); 5623 pss->trim_queue(); 5624 } 5625 }; 5626 5627 // Parallel Reference Processing closures 5628 5629 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5630 // processing during G1 evacuation pauses. 5631 5632 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5633 private: 5634 G1CollectedHeap* _g1h; 5635 RefToScanQueueSet* _queues; 5636 FlexibleWorkGang* _workers; 5637 int _active_workers; 5638 5639 public: 5640 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5641 FlexibleWorkGang* workers, 5642 RefToScanQueueSet *task_queues, 5643 int n_workers) : 5644 _g1h(g1h), 5645 _queues(task_queues), 5646 _workers(workers), 5647 _active_workers(n_workers) 5648 { 5649 assert(n_workers > 0, "shouldn't call this otherwise"); 5650 } 5651 5652 // Executes the given task using concurrent marking worker threads. 5653 virtual void execute(ProcessTask& task); 5654 virtual void execute(EnqueueTask& task); 5655 }; 5656 5657 // Gang task for possibly parallel reference processing 5658 5659 class G1STWRefProcTaskProxy: public AbstractGangTask { 5660 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5661 ProcessTask& _proc_task; 5662 G1CollectedHeap* _g1h; 5663 RefToScanQueueSet *_task_queues; 5664 ParallelTaskTerminator* _terminator; 5665 5666 public: 5667 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5668 G1CollectedHeap* g1h, 5669 RefToScanQueueSet *task_queues, 5670 ParallelTaskTerminator* terminator) : 5671 AbstractGangTask("Process reference objects in parallel"), 5672 _proc_task(proc_task), 5673 _g1h(g1h), 5674 _task_queues(task_queues), 5675 _terminator(terminator) 5676 {} 5677 5678 virtual void work(uint worker_id) { 5679 // The reference processing task executed by a single worker. 5680 ResourceMark rm; 5681 HandleMark hm; 5682 5683 G1STWIsAliveClosure is_alive(_g1h); 5684 5685 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5686 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5687 5688 pss.set_evac_failure_closure(&evac_failure_cl); 5689 5690 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5691 5692 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5693 5694 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5695 5696 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5697 // We also need to mark copied objects. 5698 copy_non_heap_cl = ©_mark_non_heap_cl; 5699 } 5700 5701 // Keep alive closure. 5702 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5703 5704 // Complete GC closure 5705 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5706 5707 // Call the reference processing task's work routine. 5708 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5709 5710 // Note we cannot assert that the refs array is empty here as not all 5711 // of the processing tasks (specifically phase2 - pp2_work) execute 5712 // the complete_gc closure (which ordinarily would drain the queue) so 5713 // the queue may not be empty. 5714 } 5715 }; 5716 5717 // Driver routine for parallel reference processing. 5718 // Creates an instance of the ref processing gang 5719 // task and has the worker threads execute it. 5720 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5721 assert(_workers != NULL, "Need parallel worker threads."); 5722 5723 ParallelTaskTerminator terminator(_active_workers, _queues); 5724 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5725 5726 _g1h->set_par_threads(_active_workers); 5727 _workers->run_task(&proc_task_proxy); 5728 _g1h->set_par_threads(0); 5729 } 5730 5731 // Gang task for parallel reference enqueueing. 5732 5733 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5734 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5735 EnqueueTask& _enq_task; 5736 5737 public: 5738 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5739 AbstractGangTask("Enqueue reference objects in parallel"), 5740 _enq_task(enq_task) 5741 { } 5742 5743 virtual void work(uint worker_id) { 5744 _enq_task.work(worker_id); 5745 } 5746 }; 5747 5748 // Driver routine for parallel reference enqueueing. 5749 // Creates an instance of the ref enqueueing gang 5750 // task and has the worker threads execute it. 5751 5752 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5753 assert(_workers != NULL, "Need parallel worker threads."); 5754 5755 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5756 5757 _g1h->set_par_threads(_active_workers); 5758 _workers->run_task(&enq_task_proxy); 5759 _g1h->set_par_threads(0); 5760 } 5761 5762 // End of weak reference support closures 5763 5764 // Abstract task used to preserve (i.e. copy) any referent objects 5765 // that are in the collection set and are pointed to by reference 5766 // objects discovered by the CM ref processor. 5767 5768 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5769 protected: 5770 G1CollectedHeap* _g1h; 5771 RefToScanQueueSet *_queues; 5772 ParallelTaskTerminator _terminator; 5773 uint _n_workers; 5774 5775 public: 5776 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5777 AbstractGangTask("ParPreserveCMReferents"), 5778 _g1h(g1h), 5779 _queues(task_queues), 5780 _terminator(workers, _queues), 5781 _n_workers(workers) 5782 { } 5783 5784 void work(uint worker_id) { 5785 ResourceMark rm; 5786 HandleMark hm; 5787 5788 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5789 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5790 5791 pss.set_evac_failure_closure(&evac_failure_cl); 5792 5793 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5794 5795 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5796 5797 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5798 5799 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5800 5801 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5802 // We also need to mark copied objects. 5803 copy_non_heap_cl = ©_mark_non_heap_cl; 5804 } 5805 5806 // Is alive closure 5807 G1AlwaysAliveClosure always_alive(_g1h); 5808 5809 // Copying keep alive closure. Applied to referent objects that need 5810 // to be copied. 5811 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5812 5813 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5814 5815 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5816 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5817 5818 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5819 // So this must be true - but assert just in case someone decides to 5820 // change the worker ids. 5821 assert(0 <= worker_id && worker_id < limit, "sanity"); 5822 assert(!rp->discovery_is_atomic(), "check this code"); 5823 5824 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5825 for (uint idx = worker_id; idx < limit; idx += stride) { 5826 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5827 5828 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5829 while (iter.has_next()) { 5830 // Since discovery is not atomic for the CM ref processor, we 5831 // can see some null referent objects. 5832 iter.load_ptrs(DEBUG_ONLY(true)); 5833 oop ref = iter.obj(); 5834 5835 // This will filter nulls. 5836 if (iter.is_referent_alive()) { 5837 iter.make_referent_alive(); 5838 } 5839 iter.move_to_next(); 5840 } 5841 } 5842 5843 // Drain the queue - which may cause stealing 5844 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5845 drain_queue.do_void(); 5846 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5847 assert(pss.queue_is_empty(), "should be"); 5848 } 5849 }; 5850 5851 // Weak Reference processing during an evacuation pause (part 1). 5852 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5853 double ref_proc_start = os::elapsedTime(); 5854 5855 ReferenceProcessor* rp = _ref_processor_stw; 5856 assert(rp->discovery_enabled(), "should have been enabled"); 5857 5858 // Any reference objects, in the collection set, that were 'discovered' 5859 // by the CM ref processor should have already been copied (either by 5860 // applying the external root copy closure to the discovered lists, or 5861 // by following an RSet entry). 5862 // 5863 // But some of the referents, that are in the collection set, that these 5864 // reference objects point to may not have been copied: the STW ref 5865 // processor would have seen that the reference object had already 5866 // been 'discovered' and would have skipped discovering the reference, 5867 // but would not have treated the reference object as a regular oop. 5868 // As a result the copy closure would not have been applied to the 5869 // referent object. 5870 // 5871 // We need to explicitly copy these referent objects - the references 5872 // will be processed at the end of remarking. 5873 // 5874 // We also need to do this copying before we process the reference 5875 // objects discovered by the STW ref processor in case one of these 5876 // referents points to another object which is also referenced by an 5877 // object discovered by the STW ref processor. 5878 5879 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5880 no_of_gc_workers == workers()->active_workers(), 5881 "Need to reset active GC workers"); 5882 5883 set_par_threads(no_of_gc_workers); 5884 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5885 no_of_gc_workers, 5886 _task_queues); 5887 5888 if (G1CollectedHeap::use_parallel_gc_threads()) { 5889 workers()->run_task(&keep_cm_referents); 5890 } else { 5891 keep_cm_referents.work(0); 5892 } 5893 5894 set_par_threads(0); 5895 5896 // Closure to test whether a referent is alive. 5897 G1STWIsAliveClosure is_alive(this); 5898 5899 // Even when parallel reference processing is enabled, the processing 5900 // of JNI refs is serial and performed serially by the current thread 5901 // rather than by a worker. The following PSS will be used for processing 5902 // JNI refs. 5903 5904 // Use only a single queue for this PSS. 5905 G1ParScanThreadState pss(this, 0, NULL); 5906 5907 // We do not embed a reference processor in the copying/scanning 5908 // closures while we're actually processing the discovered 5909 // reference objects. 5910 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5911 5912 pss.set_evac_failure_closure(&evac_failure_cl); 5913 5914 assert(pss.queue_is_empty(), "pre-condition"); 5915 5916 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5917 5918 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5919 5920 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5921 5922 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5923 // We also need to mark copied objects. 5924 copy_non_heap_cl = ©_mark_non_heap_cl; 5925 } 5926 5927 // Keep alive closure. 5928 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5929 5930 // Serial Complete GC closure 5931 G1STWDrainQueueClosure drain_queue(this, &pss); 5932 5933 // Setup the soft refs policy... 5934 rp->setup_policy(false); 5935 5936 ReferenceProcessorStats stats; 5937 if (!rp->processing_is_mt()) { 5938 // Serial reference processing... 5939 stats = rp->process_discovered_references(&is_alive, 5940 &keep_alive, 5941 &drain_queue, 5942 NULL, 5943 _gc_timer_stw, 5944 _gc_tracer_stw->gc_id()); 5945 } else { 5946 // Parallel reference processing 5947 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5948 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5949 5950 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5951 stats = rp->process_discovered_references(&is_alive, 5952 &keep_alive, 5953 &drain_queue, 5954 &par_task_executor, 5955 _gc_timer_stw, 5956 _gc_tracer_stw->gc_id()); 5957 } 5958 5959 _gc_tracer_stw->report_gc_reference_stats(stats); 5960 5961 // We have completed copying any necessary live referent objects. 5962 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5963 5964 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5965 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5966 } 5967 5968 // Weak Reference processing during an evacuation pause (part 2). 5969 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5970 double ref_enq_start = os::elapsedTime(); 5971 5972 ReferenceProcessor* rp = _ref_processor_stw; 5973 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5974 5975 // Now enqueue any remaining on the discovered lists on to 5976 // the pending list. 5977 if (!rp->processing_is_mt()) { 5978 // Serial reference processing... 5979 rp->enqueue_discovered_references(); 5980 } else { 5981 // Parallel reference enqueueing 5982 5983 assert(no_of_gc_workers == workers()->active_workers(), 5984 "Need to reset active workers"); 5985 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5986 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5987 5988 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5989 rp->enqueue_discovered_references(&par_task_executor); 5990 } 5991 5992 rp->verify_no_references_recorded(); 5993 assert(!rp->discovery_enabled(), "should have been disabled"); 5994 5995 // FIXME 5996 // CM's reference processing also cleans up the string and symbol tables. 5997 // Should we do that here also? We could, but it is a serial operation 5998 // and could significantly increase the pause time. 5999 6000 double ref_enq_time = os::elapsedTime() - ref_enq_start; 6001 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 6002 } 6003 6004 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 6005 _expand_heap_after_alloc_failure = true; 6006 _evacuation_failed = false; 6007 6008 // Should G1EvacuationFailureALot be in effect for this GC? 6009 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 6010 6011 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 6012 6013 // Disable the hot card cache. 6014 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 6015 hot_card_cache->reset_hot_cache_claimed_index(); 6016 hot_card_cache->set_use_cache(false); 6017 6018 uint n_workers; 6019 if (G1CollectedHeap::use_parallel_gc_threads()) { 6020 n_workers = 6021 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 6022 workers()->active_workers(), 6023 Threads::number_of_non_daemon_threads()); 6024 assert(UseDynamicNumberOfGCThreads || 6025 n_workers == workers()->total_workers(), 6026 "If not dynamic should be using all the workers"); 6027 workers()->set_active_workers(n_workers); 6028 set_par_threads(n_workers); 6029 } else { 6030 assert(n_par_threads() == 0, 6031 "Should be the original non-parallel value"); 6032 n_workers = 1; 6033 } 6034 6035 G1ParTask g1_par_task(this, _task_queues); 6036 6037 init_for_evac_failure(NULL); 6038 6039 rem_set()->prepare_for_younger_refs_iterate(true); 6040 6041 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 6042 double start_par_time_sec = os::elapsedTime(); 6043 double end_par_time_sec; 6044 6045 { 6046 StrongRootsScope srs(this); 6047 // InitialMark needs claim bits to keep track of the marked-through CLDs. 6048 if (g1_policy()->during_initial_mark_pause()) { 6049 ClassLoaderDataGraph::clear_claimed_marks(); 6050 } 6051 6052 if (G1CollectedHeap::use_parallel_gc_threads()) { 6053 // The individual threads will set their evac-failure closures. 6054 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 6055 // These tasks use ShareHeap::_process_strong_tasks 6056 assert(UseDynamicNumberOfGCThreads || 6057 workers()->active_workers() == workers()->total_workers(), 6058 "If not dynamic should be using all the workers"); 6059 workers()->run_task(&g1_par_task); 6060 } else { 6061 g1_par_task.set_for_termination(n_workers); 6062 g1_par_task.work(0); 6063 } 6064 end_par_time_sec = os::elapsedTime(); 6065 6066 // Closing the inner scope will execute the destructor 6067 // for the StrongRootsScope object. We record the current 6068 // elapsed time before closing the scope so that time 6069 // taken for the SRS destructor is NOT included in the 6070 // reported parallel time. 6071 } 6072 6073 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 6074 g1_policy()->phase_times()->record_par_time(par_time_ms); 6075 6076 double code_root_fixup_time_ms = 6077 (os::elapsedTime() - end_par_time_sec) * 1000.0; 6078 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 6079 6080 set_par_threads(0); 6081 6082 // Process any discovered reference objects - we have 6083 // to do this _before_ we retire the GC alloc regions 6084 // as we may have to copy some 'reachable' referent 6085 // objects (and their reachable sub-graphs) that were 6086 // not copied during the pause. 6087 process_discovered_references(n_workers); 6088 6089 // Weak root processing. 6090 { 6091 G1STWIsAliveClosure is_alive(this); 6092 G1KeepAliveClosure keep_alive(this); 6093 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 6094 if (G1StringDedup::is_enabled()) { 6095 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 6096 } 6097 } 6098 6099 release_gc_alloc_regions(n_workers, evacuation_info); 6100 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 6101 6102 // Reset and re-enable the hot card cache. 6103 // Note the counts for the cards in the regions in the 6104 // collection set are reset when the collection set is freed. 6105 hot_card_cache->reset_hot_cache(); 6106 hot_card_cache->set_use_cache(true); 6107 6108 // Migrate the strong code roots attached to each region in 6109 // the collection set. Ideally we would like to do this 6110 // after we have finished the scanning/evacuation of the 6111 // strong code roots for a particular heap region. 6112 migrate_strong_code_roots(); 6113 6114 purge_code_root_memory(); 6115 6116 if (g1_policy()->during_initial_mark_pause()) { 6117 // Reset the claim values set during marking the strong code roots 6118 reset_heap_region_claim_values(); 6119 } 6120 6121 finalize_for_evac_failure(); 6122 6123 if (evacuation_failed()) { 6124 remove_self_forwarding_pointers(); 6125 6126 // Reset the G1EvacuationFailureALot counters and flags 6127 // Note: the values are reset only when an actual 6128 // evacuation failure occurs. 6129 NOT_PRODUCT(reset_evacuation_should_fail();) 6130 } 6131 6132 // Enqueue any remaining references remaining on the STW 6133 // reference processor's discovered lists. We need to do 6134 // this after the card table is cleaned (and verified) as 6135 // the act of enqueueing entries on to the pending list 6136 // will log these updates (and dirty their associated 6137 // cards). We need these updates logged to update any 6138 // RSets. 6139 enqueue_discovered_references(n_workers); 6140 6141 if (G1DeferredRSUpdate) { 6142 redirty_logged_cards(); 6143 } 6144 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 6145 } 6146 6147 void G1CollectedHeap::free_region(HeapRegion* hr, 6148 FreeRegionList* free_list, 6149 bool par, 6150 bool locked) { 6151 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 6152 assert(!hr->is_empty(), "the region should not be empty"); 6153 assert(free_list != NULL, "pre-condition"); 6154 6155 if (G1VerifyBitmaps) { 6156 MemRegion mr(hr->bottom(), hr->end()); 6157 concurrent_mark()->clearRangePrevBitmap(mr); 6158 } 6159 6160 // Clear the card counts for this region. 6161 // Note: we only need to do this if the region is not young 6162 // (since we don't refine cards in young regions). 6163 if (!hr->is_young()) { 6164 _cg1r->hot_card_cache()->reset_card_counts(hr); 6165 } 6166 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 6167 free_list->add_ordered(hr); 6168 } 6169 6170 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 6171 FreeRegionList* free_list, 6172 bool par) { 6173 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 6174 assert(free_list != NULL, "pre-condition"); 6175 6176 size_t hr_capacity = hr->capacity(); 6177 // We need to read this before we make the region non-humongous, 6178 // otherwise the information will be gone. 6179 uint last_index = hr->last_hc_index(); 6180 hr->set_notHumongous(); 6181 free_region(hr, free_list, par); 6182 6183 uint i = hr->hrs_index() + 1; 6184 while (i < last_index) { 6185 HeapRegion* curr_hr = region_at(i); 6186 assert(curr_hr->continuesHumongous(), "invariant"); 6187 curr_hr->set_notHumongous(); 6188 free_region(curr_hr, free_list, par); 6189 i += 1; 6190 } 6191 } 6192 6193 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 6194 const HeapRegionSetCount& humongous_regions_removed) { 6195 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 6196 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6197 _old_set.bulk_remove(old_regions_removed); 6198 _humongous_set.bulk_remove(humongous_regions_removed); 6199 } 6200 6201 } 6202 6203 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 6204 assert(list != NULL, "list can't be null"); 6205 if (!list->is_empty()) { 6206 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6207 _free_list.add_ordered(list); 6208 } 6209 } 6210 6211 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6212 assert(_summary_bytes_used >= bytes, 6213 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 6214 _summary_bytes_used, bytes)); 6215 _summary_bytes_used -= bytes; 6216 } 6217 6218 class G1ParCleanupCTTask : public AbstractGangTask { 6219 G1SATBCardTableModRefBS* _ct_bs; 6220 G1CollectedHeap* _g1h; 6221 HeapRegion* volatile _su_head; 6222 public: 6223 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6224 G1CollectedHeap* g1h) : 6225 AbstractGangTask("G1 Par Cleanup CT Task"), 6226 _ct_bs(ct_bs), _g1h(g1h) { } 6227 6228 void work(uint worker_id) { 6229 HeapRegion* r; 6230 while (r = _g1h->pop_dirty_cards_region()) { 6231 clear_cards(r); 6232 } 6233 } 6234 6235 void clear_cards(HeapRegion* r) { 6236 // Cards of the survivors should have already been dirtied. 6237 if (!r->is_survivor()) { 6238 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6239 } 6240 } 6241 }; 6242 6243 #ifndef PRODUCT 6244 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6245 G1CollectedHeap* _g1h; 6246 G1SATBCardTableModRefBS* _ct_bs; 6247 public: 6248 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6249 : _g1h(g1h), _ct_bs(ct_bs) { } 6250 virtual bool doHeapRegion(HeapRegion* r) { 6251 if (r->is_survivor()) { 6252 _g1h->verify_dirty_region(r); 6253 } else { 6254 _g1h->verify_not_dirty_region(r); 6255 } 6256 return false; 6257 } 6258 }; 6259 6260 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6261 // All of the region should be clean. 6262 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6263 MemRegion mr(hr->bottom(), hr->end()); 6264 ct_bs->verify_not_dirty_region(mr); 6265 } 6266 6267 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6268 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6269 // dirty allocated blocks as they allocate them. The thread that 6270 // retires each region and replaces it with a new one will do a 6271 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6272 // not dirty that area (one less thing to have to do while holding 6273 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6274 // is dirty. 6275 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6276 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6277 if (hr->is_young()) { 6278 ct_bs->verify_g1_young_region(mr); 6279 } else { 6280 ct_bs->verify_dirty_region(mr); 6281 } 6282 } 6283 6284 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6285 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6286 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6287 verify_dirty_region(hr); 6288 } 6289 } 6290 6291 void G1CollectedHeap::verify_dirty_young_regions() { 6292 verify_dirty_young_list(_young_list->first_region()); 6293 } 6294 6295 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 6296 HeapWord* tams, HeapWord* end) { 6297 guarantee(tams <= end, 6298 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 6299 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 6300 if (result < end) { 6301 gclog_or_tty->cr(); 6302 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 6303 bitmap_name, result); 6304 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 6305 bitmap_name, tams, end); 6306 return false; 6307 } 6308 return true; 6309 } 6310 6311 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 6312 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 6313 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 6314 6315 HeapWord* bottom = hr->bottom(); 6316 HeapWord* ptams = hr->prev_top_at_mark_start(); 6317 HeapWord* ntams = hr->next_top_at_mark_start(); 6318 HeapWord* end = hr->end(); 6319 6320 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 6321 6322 bool res_n = true; 6323 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 6324 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 6325 // if we happen to be in that state. 6326 if (mark_in_progress() || !_cmThread->in_progress()) { 6327 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 6328 } 6329 if (!res_p || !res_n) { 6330 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 6331 HR_FORMAT_PARAMS(hr)); 6332 gclog_or_tty->print_cr("#### Caller: %s", caller); 6333 return false; 6334 } 6335 return true; 6336 } 6337 6338 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 6339 if (!G1VerifyBitmaps) return; 6340 6341 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 6342 } 6343 6344 class G1VerifyBitmapClosure : public HeapRegionClosure { 6345 private: 6346 const char* _caller; 6347 G1CollectedHeap* _g1h; 6348 bool _failures; 6349 6350 public: 6351 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 6352 _caller(caller), _g1h(g1h), _failures(false) { } 6353 6354 bool failures() { return _failures; } 6355 6356 virtual bool doHeapRegion(HeapRegion* hr) { 6357 if (hr->continuesHumongous()) return false; 6358 6359 bool result = _g1h->verify_bitmaps(_caller, hr); 6360 if (!result) { 6361 _failures = true; 6362 } 6363 return false; 6364 } 6365 }; 6366 6367 void G1CollectedHeap::check_bitmaps(const char* caller) { 6368 if (!G1VerifyBitmaps) return; 6369 6370 G1VerifyBitmapClosure cl(caller, this); 6371 heap_region_iterate(&cl); 6372 guarantee(!cl.failures(), "bitmap verification"); 6373 } 6374 #endif // PRODUCT 6375 6376 void G1CollectedHeap::cleanUpCardTable() { 6377 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6378 double start = os::elapsedTime(); 6379 6380 { 6381 // Iterate over the dirty cards region list. 6382 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6383 6384 if (G1CollectedHeap::use_parallel_gc_threads()) { 6385 set_par_threads(); 6386 workers()->run_task(&cleanup_task); 6387 set_par_threads(0); 6388 } else { 6389 while (_dirty_cards_region_list) { 6390 HeapRegion* r = _dirty_cards_region_list; 6391 cleanup_task.clear_cards(r); 6392 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6393 if (_dirty_cards_region_list == r) { 6394 // The last region. 6395 _dirty_cards_region_list = NULL; 6396 } 6397 r->set_next_dirty_cards_region(NULL); 6398 } 6399 } 6400 #ifndef PRODUCT 6401 if (G1VerifyCTCleanup || VerifyAfterGC) { 6402 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6403 heap_region_iterate(&cleanup_verifier); 6404 } 6405 #endif 6406 } 6407 6408 double elapsed = os::elapsedTime() - start; 6409 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6410 } 6411 6412 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6413 size_t pre_used = 0; 6414 FreeRegionList local_free_list("Local List for CSet Freeing"); 6415 6416 double young_time_ms = 0.0; 6417 double non_young_time_ms = 0.0; 6418 6419 // Since the collection set is a superset of the the young list, 6420 // all we need to do to clear the young list is clear its 6421 // head and length, and unlink any young regions in the code below 6422 _young_list->clear(); 6423 6424 G1CollectorPolicy* policy = g1_policy(); 6425 6426 double start_sec = os::elapsedTime(); 6427 bool non_young = true; 6428 6429 HeapRegion* cur = cs_head; 6430 int age_bound = -1; 6431 size_t rs_lengths = 0; 6432 6433 while (cur != NULL) { 6434 assert(!is_on_master_free_list(cur), "sanity"); 6435 if (non_young) { 6436 if (cur->is_young()) { 6437 double end_sec = os::elapsedTime(); 6438 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6439 non_young_time_ms += elapsed_ms; 6440 6441 start_sec = os::elapsedTime(); 6442 non_young = false; 6443 } 6444 } else { 6445 if (!cur->is_young()) { 6446 double end_sec = os::elapsedTime(); 6447 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6448 young_time_ms += elapsed_ms; 6449 6450 start_sec = os::elapsedTime(); 6451 non_young = true; 6452 } 6453 } 6454 6455 rs_lengths += cur->rem_set()->occupied_locked(); 6456 6457 HeapRegion* next = cur->next_in_collection_set(); 6458 assert(cur->in_collection_set(), "bad CS"); 6459 cur->set_next_in_collection_set(NULL); 6460 cur->set_in_collection_set(false); 6461 6462 if (cur->is_young()) { 6463 int index = cur->young_index_in_cset(); 6464 assert(index != -1, "invariant"); 6465 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6466 size_t words_survived = _surviving_young_words[index]; 6467 cur->record_surv_words_in_group(words_survived); 6468 6469 // At this point the we have 'popped' cur from the collection set 6470 // (linked via next_in_collection_set()) but it is still in the 6471 // young list (linked via next_young_region()). Clear the 6472 // _next_young_region field. 6473 cur->set_next_young_region(NULL); 6474 } else { 6475 int index = cur->young_index_in_cset(); 6476 assert(index == -1, "invariant"); 6477 } 6478 6479 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6480 (!cur->is_young() && cur->young_index_in_cset() == -1), 6481 "invariant" ); 6482 6483 if (!cur->evacuation_failed()) { 6484 MemRegion used_mr = cur->used_region(); 6485 6486 // And the region is empty. 6487 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6488 pre_used += cur->used(); 6489 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6490 } else { 6491 cur->uninstall_surv_rate_group(); 6492 if (cur->is_young()) { 6493 cur->set_young_index_in_cset(-1); 6494 } 6495 cur->set_not_young(); 6496 cur->set_evacuation_failed(false); 6497 // The region is now considered to be old. 6498 _old_set.add(cur); 6499 evacuation_info.increment_collectionset_used_after(cur->used()); 6500 } 6501 cur = next; 6502 } 6503 6504 evacuation_info.set_regions_freed(local_free_list.length()); 6505 policy->record_max_rs_lengths(rs_lengths); 6506 policy->cset_regions_freed(); 6507 6508 double end_sec = os::elapsedTime(); 6509 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6510 6511 if (non_young) { 6512 non_young_time_ms += elapsed_ms; 6513 } else { 6514 young_time_ms += elapsed_ms; 6515 } 6516 6517 prepend_to_freelist(&local_free_list); 6518 decrement_summary_bytes(pre_used); 6519 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6520 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6521 } 6522 6523 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6524 private: 6525 FreeRegionList* _free_region_list; 6526 HeapRegionSet* _proxy_set; 6527 HeapRegionSetCount _humongous_regions_removed; 6528 size_t _freed_bytes; 6529 public: 6530 6531 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6532 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6533 } 6534 6535 virtual bool doHeapRegion(HeapRegion* r) { 6536 if (!r->startsHumongous()) { 6537 return false; 6538 } 6539 6540 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6541 6542 oop obj = (oop)r->bottom(); 6543 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6544 6545 // The following checks whether the humongous object is live are sufficient. 6546 // The main additional check (in addition to having a reference from the roots 6547 // or the young gen) is whether the humongous object has a remembered set entry. 6548 // 6549 // A humongous object cannot be live if there is no remembered set for it 6550 // because: 6551 // - there can be no references from within humongous starts regions referencing 6552 // the object because we never allocate other objects into them. 6553 // (I.e. there are no intra-region references that may be missed by the 6554 // remembered set) 6555 // - as soon there is a remembered set entry to the humongous starts region 6556 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6557 // until the end of a concurrent mark. 6558 // 6559 // It is not required to check whether the object has been found dead by marking 6560 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6561 // all objects allocated during that time are considered live. 6562 // SATB marking is even more conservative than the remembered set. 6563 // So if at this point in the collection there is no remembered set entry, 6564 // nobody has a reference to it. 6565 // At the start of collection we flush all refinement logs, and remembered sets 6566 // are completely up-to-date wrt to references to the humongous object. 6567 // 6568 // Other implementation considerations: 6569 // - never consider object arrays: while they are a valid target, they have not 6570 // been observed to be used as temporary objects. 6571 // - they would also pose considerable effort for cleaning up the the remembered 6572 // sets. 6573 // While this cleanup is not strictly necessary to be done (or done instantly), 6574 // given that their occurrence is very low, this saves us this additional 6575 // complexity. 6576 uint region_idx = r->hrs_index(); 6577 if (g1h->humongous_is_live(region_idx) || 6578 g1h->humongous_region_is_always_live(region_idx)) { 6579 6580 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6581 gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6582 r->isHumongous(), 6583 region_idx, 6584 r->rem_set()->occupied(), 6585 r->rem_set()->strong_code_roots_list_length(), 6586 next_bitmap->isMarked(r->bottom()), 6587 g1h->humongous_is_live(region_idx), 6588 obj->is_objArray() 6589 ); 6590 } 6591 6592 return false; 6593 } 6594 6595 guarantee(!obj->is_objArray(), 6596 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6597 r->bottom())); 6598 6599 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6600 gclog_or_tty->print_cr("Reclaim humongous region %d start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6601 r->isHumongous(), 6602 r->bottom(), 6603 region_idx, 6604 r->region_num(), 6605 r->rem_set()->occupied(), 6606 r->rem_set()->strong_code_roots_list_length(), 6607 next_bitmap->isMarked(r->bottom()), 6608 g1h->humongous_is_live(region_idx), 6609 obj->is_objArray() 6610 ); 6611 } 6612 // Need to clear mark bit of the humongous object if already set. 6613 if (next_bitmap->isMarked(r->bottom())) { 6614 next_bitmap->clear(r->bottom()); 6615 } 6616 _freed_bytes += r->used(); 6617 r->set_containing_set(NULL); 6618 _humongous_regions_removed.increment(1u, r->capacity()); 6619 g1h->free_humongous_region(r, _free_region_list, false); 6620 6621 return false; 6622 } 6623 6624 HeapRegionSetCount& humongous_free_count() { 6625 return _humongous_regions_removed; 6626 } 6627 6628 size_t bytes_freed() const { 6629 return _freed_bytes; 6630 } 6631 6632 size_t humongous_reclaimed() const { 6633 return _humongous_regions_removed.length(); 6634 } 6635 }; 6636 6637 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6638 assert_at_safepoint(true); 6639 6640 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) { 6641 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6642 return; 6643 } 6644 6645 double start_time = os::elapsedTime(); 6646 6647 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6648 6649 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6650 heap_region_iterate(&cl); 6651 6652 HeapRegionSetCount empty_set; 6653 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6654 6655 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6656 if (hr_printer->is_active()) { 6657 FreeRegionListIterator iter(&local_cleanup_list); 6658 while (iter.more_available()) { 6659 HeapRegion* hr = iter.get_next(); 6660 hr_printer->cleanup(hr); 6661 } 6662 } 6663 6664 prepend_to_freelist(&local_cleanup_list); 6665 decrement_summary_bytes(cl.bytes_freed()); 6666 6667 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6668 cl.humongous_reclaimed()); 6669 } 6670 6671 // This routine is similar to the above but does not record 6672 // any policy statistics or update free lists; we are abandoning 6673 // the current incremental collection set in preparation of a 6674 // full collection. After the full GC we will start to build up 6675 // the incremental collection set again. 6676 // This is only called when we're doing a full collection 6677 // and is immediately followed by the tearing down of the young list. 6678 6679 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6680 HeapRegion* cur = cs_head; 6681 6682 while (cur != NULL) { 6683 HeapRegion* next = cur->next_in_collection_set(); 6684 assert(cur->in_collection_set(), "bad CS"); 6685 cur->set_next_in_collection_set(NULL); 6686 cur->set_in_collection_set(false); 6687 cur->set_young_index_in_cset(-1); 6688 cur = next; 6689 } 6690 } 6691 6692 void G1CollectedHeap::set_free_regions_coming() { 6693 if (G1ConcRegionFreeingVerbose) { 6694 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6695 "setting free regions coming"); 6696 } 6697 6698 assert(!free_regions_coming(), "pre-condition"); 6699 _free_regions_coming = true; 6700 } 6701 6702 void G1CollectedHeap::reset_free_regions_coming() { 6703 assert(free_regions_coming(), "pre-condition"); 6704 6705 { 6706 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6707 _free_regions_coming = false; 6708 SecondaryFreeList_lock->notify_all(); 6709 } 6710 6711 if (G1ConcRegionFreeingVerbose) { 6712 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6713 "reset free regions coming"); 6714 } 6715 } 6716 6717 void G1CollectedHeap::wait_while_free_regions_coming() { 6718 // Most of the time we won't have to wait, so let's do a quick test 6719 // first before we take the lock. 6720 if (!free_regions_coming()) { 6721 return; 6722 } 6723 6724 if (G1ConcRegionFreeingVerbose) { 6725 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6726 "waiting for free regions"); 6727 } 6728 6729 { 6730 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6731 while (free_regions_coming()) { 6732 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6733 } 6734 } 6735 6736 if (G1ConcRegionFreeingVerbose) { 6737 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6738 "done waiting for free regions"); 6739 } 6740 } 6741 6742 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6743 assert(heap_lock_held_for_gc(), 6744 "the heap lock should already be held by or for this thread"); 6745 _young_list->push_region(hr); 6746 } 6747 6748 class NoYoungRegionsClosure: public HeapRegionClosure { 6749 private: 6750 bool _success; 6751 public: 6752 NoYoungRegionsClosure() : _success(true) { } 6753 bool doHeapRegion(HeapRegion* r) { 6754 if (r->is_young()) { 6755 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6756 r->bottom(), r->end()); 6757 _success = false; 6758 } 6759 return false; 6760 } 6761 bool success() { return _success; } 6762 }; 6763 6764 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6765 bool ret = _young_list->check_list_empty(check_sample); 6766 6767 if (check_heap) { 6768 NoYoungRegionsClosure closure; 6769 heap_region_iterate(&closure); 6770 ret = ret && closure.success(); 6771 } 6772 6773 return ret; 6774 } 6775 6776 class TearDownRegionSetsClosure : public HeapRegionClosure { 6777 private: 6778 HeapRegionSet *_old_set; 6779 6780 public: 6781 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6782 6783 bool doHeapRegion(HeapRegion* r) { 6784 if (r->is_empty()) { 6785 // We ignore empty regions, we'll empty the free list afterwards 6786 } else if (r->is_young()) { 6787 // We ignore young regions, we'll empty the young list afterwards 6788 } else if (r->isHumongous()) { 6789 // We ignore humongous regions, we're not tearing down the 6790 // humongous region set 6791 } else { 6792 // The rest should be old 6793 _old_set->remove(r); 6794 } 6795 return false; 6796 } 6797 6798 ~TearDownRegionSetsClosure() { 6799 assert(_old_set->is_empty(), "post-condition"); 6800 } 6801 }; 6802 6803 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6804 assert_at_safepoint(true /* should_be_vm_thread */); 6805 6806 if (!free_list_only) { 6807 TearDownRegionSetsClosure cl(&_old_set); 6808 heap_region_iterate(&cl); 6809 6810 // Note that emptying the _young_list is postponed and instead done as 6811 // the first step when rebuilding the regions sets again. The reason for 6812 // this is that during a full GC string deduplication needs to know if 6813 // a collected region was young or old when the full GC was initiated. 6814 } 6815 _free_list.remove_all(); 6816 } 6817 6818 class RebuildRegionSetsClosure : public HeapRegionClosure { 6819 private: 6820 bool _free_list_only; 6821 HeapRegionSet* _old_set; 6822 FreeRegionList* _free_list; 6823 size_t _total_used; 6824 6825 public: 6826 RebuildRegionSetsClosure(bool free_list_only, 6827 HeapRegionSet* old_set, FreeRegionList* free_list) : 6828 _free_list_only(free_list_only), 6829 _old_set(old_set), _free_list(free_list), _total_used(0) { 6830 assert(_free_list->is_empty(), "pre-condition"); 6831 if (!free_list_only) { 6832 assert(_old_set->is_empty(), "pre-condition"); 6833 } 6834 } 6835 6836 bool doHeapRegion(HeapRegion* r) { 6837 if (r->continuesHumongous()) { 6838 return false; 6839 } 6840 6841 if (r->is_empty()) { 6842 // Add free regions to the free list 6843 _free_list->add_as_tail(r); 6844 } else if (!_free_list_only) { 6845 assert(!r->is_young(), "we should not come across young regions"); 6846 6847 if (r->isHumongous()) { 6848 // We ignore humongous regions, we left the humongous set unchanged 6849 } else { 6850 // The rest should be old, add them to the old set 6851 _old_set->add(r); 6852 } 6853 _total_used += r->used(); 6854 } 6855 6856 return false; 6857 } 6858 6859 size_t total_used() { 6860 return _total_used; 6861 } 6862 }; 6863 6864 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6865 assert_at_safepoint(true /* should_be_vm_thread */); 6866 6867 if (!free_list_only) { 6868 _young_list->empty_list(); 6869 } 6870 6871 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6872 heap_region_iterate(&cl); 6873 6874 if (!free_list_only) { 6875 _summary_bytes_used = cl.total_used(); 6876 } 6877 assert(_summary_bytes_used == recalculate_used(), 6878 err_msg("inconsistent _summary_bytes_used, " 6879 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6880 _summary_bytes_used, recalculate_used())); 6881 } 6882 6883 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6884 _refine_cte_cl->set_concurrent(concurrent); 6885 } 6886 6887 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6888 HeapRegion* hr = heap_region_containing(p); 6889 return hr->is_in(p); 6890 } 6891 6892 // Methods for the mutator alloc region 6893 6894 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6895 bool force) { 6896 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6897 assert(!force || g1_policy()->can_expand_young_list(), 6898 "if force is true we should be able to expand the young list"); 6899 bool young_list_full = g1_policy()->is_young_list_full(); 6900 if (force || !young_list_full) { 6901 HeapRegion* new_alloc_region = new_region(word_size, 6902 false /* is_old */, 6903 false /* do_expand */); 6904 if (new_alloc_region != NULL) { 6905 set_region_short_lived_locked(new_alloc_region); 6906 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6907 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6908 return new_alloc_region; 6909 } 6910 } 6911 return NULL; 6912 } 6913 6914 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6915 size_t allocated_bytes) { 6916 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6917 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6918 6919 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6920 _summary_bytes_used += allocated_bytes; 6921 _hr_printer.retire(alloc_region); 6922 // We update the eden sizes here, when the region is retired, 6923 // instead of when it's allocated, since this is the point that its 6924 // used space has been recored in _summary_bytes_used. 6925 g1mm()->update_eden_size(); 6926 } 6927 6928 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6929 bool force) { 6930 return _g1h->new_mutator_alloc_region(word_size, force); 6931 } 6932 6933 void G1CollectedHeap::set_par_threads() { 6934 // Don't change the number of workers. Use the value previously set 6935 // in the workgroup. 6936 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6937 uint n_workers = workers()->active_workers(); 6938 assert(UseDynamicNumberOfGCThreads || 6939 n_workers == workers()->total_workers(), 6940 "Otherwise should be using the total number of workers"); 6941 if (n_workers == 0) { 6942 assert(false, "Should have been set in prior evacuation pause."); 6943 n_workers = ParallelGCThreads; 6944 workers()->set_active_workers(n_workers); 6945 } 6946 set_par_threads(n_workers); 6947 } 6948 6949 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6950 size_t allocated_bytes) { 6951 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6952 } 6953 6954 // Methods for the GC alloc regions 6955 6956 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6957 uint count, 6958 GCAllocPurpose ap) { 6959 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6960 6961 if (count < g1_policy()->max_regions(ap)) { 6962 bool survivor = (ap == GCAllocForSurvived); 6963 HeapRegion* new_alloc_region = new_region(word_size, 6964 !survivor, 6965 true /* do_expand */); 6966 if (new_alloc_region != NULL) { 6967 // We really only need to do this for old regions given that we 6968 // should never scan survivors. But it doesn't hurt to do it 6969 // for survivors too. 6970 new_alloc_region->record_top_and_timestamp(); 6971 if (survivor) { 6972 new_alloc_region->set_survivor(); 6973 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6974 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6975 } else { 6976 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6977 check_bitmaps("Old Region Allocation", new_alloc_region); 6978 } 6979 bool during_im = g1_policy()->during_initial_mark_pause(); 6980 new_alloc_region->note_start_of_copying(during_im); 6981 return new_alloc_region; 6982 } else { 6983 g1_policy()->note_alloc_region_limit_reached(ap); 6984 } 6985 } 6986 return NULL; 6987 } 6988 6989 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6990 size_t allocated_bytes, 6991 GCAllocPurpose ap) { 6992 bool during_im = g1_policy()->during_initial_mark_pause(); 6993 alloc_region->note_end_of_copying(during_im); 6994 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6995 if (ap == GCAllocForSurvived) { 6996 young_list()->add_survivor_region(alloc_region); 6997 } else { 6998 _old_set.add(alloc_region); 6999 } 7000 _hr_printer.retire(alloc_region); 7001 } 7002 7003 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 7004 bool force) { 7005 assert(!force, "not supported for GC alloc regions"); 7006 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 7007 } 7008 7009 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 7010 size_t allocated_bytes) { 7011 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 7012 GCAllocForSurvived); 7013 } 7014 7015 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 7016 bool force) { 7017 assert(!force, "not supported for GC alloc regions"); 7018 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 7019 } 7020 7021 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 7022 size_t allocated_bytes) { 7023 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 7024 GCAllocForTenured); 7025 } 7026 // Heap region set verification 7027 7028 class VerifyRegionListsClosure : public HeapRegionClosure { 7029 private: 7030 HeapRegionSet* _old_set; 7031 HeapRegionSet* _humongous_set; 7032 FreeRegionList* _free_list; 7033 7034 public: 7035 HeapRegionSetCount _old_count; 7036 HeapRegionSetCount _humongous_count; 7037 HeapRegionSetCount _free_count; 7038 7039 VerifyRegionListsClosure(HeapRegionSet* old_set, 7040 HeapRegionSet* humongous_set, 7041 FreeRegionList* free_list) : 7042 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list), 7043 _old_count(), _humongous_count(), _free_count(){ } 7044 7045 bool doHeapRegion(HeapRegion* hr) { 7046 if (hr->continuesHumongous()) { 7047 return false; 7048 } 7049 7050 if (hr->is_young()) { 7051 // TODO 7052 } else if (hr->startsHumongous()) { 7053 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index())); 7054 _humongous_count.increment(1u, hr->capacity()); 7055 } else if (hr->is_empty()) { 7056 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index())); 7057 _free_count.increment(1u, hr->capacity()); 7058 } else { 7059 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index())); 7060 _old_count.increment(1u, hr->capacity()); 7061 } 7062 return false; 7063 } 7064 7065 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) { 7066 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 7067 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 7068 old_set->total_capacity_bytes(), _old_count.capacity())); 7069 7070 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 7071 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 7072 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 7073 7074 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length())); 7075 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 7076 free_list->total_capacity_bytes(), _free_count.capacity())); 7077 } 7078 }; 7079 7080 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 7081 HeapWord* bottom) { 7082 HeapWord* end = bottom + HeapRegion::GrainWords; 7083 MemRegion mr(bottom, end); 7084 assert(_g1_reserved.contains(mr), "invariant"); 7085 // This might return NULL if the allocation fails 7086 return new HeapRegion(hrs_index, _bot_shared, mr); 7087 } 7088 7089 void G1CollectedHeap::verify_region_sets() { 7090 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 7091 7092 // First, check the explicit lists. 7093 _free_list.verify_list(); 7094 { 7095 // Given that a concurrent operation might be adding regions to 7096 // the secondary free list we have to take the lock before 7097 // verifying it. 7098 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 7099 _secondary_free_list.verify_list(); 7100 } 7101 7102 // If a concurrent region freeing operation is in progress it will 7103 // be difficult to correctly attributed any free regions we come 7104 // across to the correct free list given that they might belong to 7105 // one of several (free_list, secondary_free_list, any local lists, 7106 // etc.). So, if that's the case we will skip the rest of the 7107 // verification operation. Alternatively, waiting for the concurrent 7108 // operation to complete will have a non-trivial effect on the GC's 7109 // operation (no concurrent operation will last longer than the 7110 // interval between two calls to verification) and it might hide 7111 // any issues that we would like to catch during testing. 7112 if (free_regions_coming()) { 7113 return; 7114 } 7115 7116 // Make sure we append the secondary_free_list on the free_list so 7117 // that all free regions we will come across can be safely 7118 // attributed to the free_list. 7119 append_secondary_free_list_if_not_empty_with_lock(); 7120 7121 // Finally, make sure that the region accounting in the lists is 7122 // consistent with what we see in the heap. 7123 7124 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 7125 heap_region_iterate(&cl); 7126 cl.verify_counts(&_old_set, &_humongous_set, &_free_list); 7127 } 7128 7129 // Optimized nmethod scanning 7130 7131 class RegisterNMethodOopClosure: public OopClosure { 7132 G1CollectedHeap* _g1h; 7133 nmethod* _nm; 7134 7135 template <class T> void do_oop_work(T* p) { 7136 T heap_oop = oopDesc::load_heap_oop(p); 7137 if (!oopDesc::is_null(heap_oop)) { 7138 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 7139 HeapRegion* hr = _g1h->heap_region_containing(obj); 7140 assert(!hr->continuesHumongous(), 7141 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 7142 " starting at "HR_FORMAT, 7143 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 7144 7145 // HeapRegion::add_strong_code_root() avoids adding duplicate 7146 // entries but having duplicates is OK since we "mark" nmethods 7147 // as visited when we scan the strong code root lists during the GC. 7148 hr->add_strong_code_root(_nm); 7149 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 7150 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 7151 _nm, HR_FORMAT_PARAMS(hr))); 7152 } 7153 } 7154 7155 public: 7156 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 7157 _g1h(g1h), _nm(nm) {} 7158 7159 void do_oop(oop* p) { do_oop_work(p); } 7160 void do_oop(narrowOop* p) { do_oop_work(p); } 7161 }; 7162 7163 class UnregisterNMethodOopClosure: public OopClosure { 7164 G1CollectedHeap* _g1h; 7165 nmethod* _nm; 7166 7167 template <class T> void do_oop_work(T* p) { 7168 T heap_oop = oopDesc::load_heap_oop(p); 7169 if (!oopDesc::is_null(heap_oop)) { 7170 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 7171 HeapRegion* hr = _g1h->heap_region_containing(obj); 7172 assert(!hr->continuesHumongous(), 7173 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 7174 " starting at "HR_FORMAT, 7175 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 7176 7177 hr->remove_strong_code_root(_nm); 7178 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 7179 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 7180 _nm, HR_FORMAT_PARAMS(hr))); 7181 } 7182 } 7183 7184 public: 7185 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 7186 _g1h(g1h), _nm(nm) {} 7187 7188 void do_oop(oop* p) { do_oop_work(p); } 7189 void do_oop(narrowOop* p) { do_oop_work(p); } 7190 }; 7191 7192 void G1CollectedHeap::register_nmethod(nmethod* nm) { 7193 CollectedHeap::register_nmethod(nm); 7194 7195 guarantee(nm != NULL, "sanity"); 7196 RegisterNMethodOopClosure reg_cl(this, nm); 7197 nm->oops_do(®_cl); 7198 } 7199 7200 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 7201 CollectedHeap::unregister_nmethod(nm); 7202 7203 guarantee(nm != NULL, "sanity"); 7204 UnregisterNMethodOopClosure reg_cl(this, nm); 7205 nm->oops_do(®_cl, true); 7206 } 7207 7208 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 7209 public: 7210 bool doHeapRegion(HeapRegion *hr) { 7211 assert(!hr->isHumongous(), 7212 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 7213 HR_FORMAT_PARAMS(hr))); 7214 hr->migrate_strong_code_roots(); 7215 return false; 7216 } 7217 }; 7218 7219 void G1CollectedHeap::migrate_strong_code_roots() { 7220 MigrateCodeRootsHeapRegionClosure cl; 7221 double migrate_start = os::elapsedTime(); 7222 collection_set_iterate(&cl); 7223 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 7224 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 7225 } 7226 7227 void G1CollectedHeap::purge_code_root_memory() { 7228 double purge_start = os::elapsedTime(); 7229 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent); 7230 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 7231 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 7232 } 7233 7234 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 7235 G1CollectedHeap* _g1h; 7236 7237 public: 7238 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 7239 _g1h(g1h) {} 7240 7241 void do_code_blob(CodeBlob* cb) { 7242 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 7243 if (nm == NULL) { 7244 return; 7245 } 7246 7247 if (ScavengeRootsInCode) { 7248 _g1h->register_nmethod(nm); 7249 } 7250 } 7251 }; 7252 7253 void G1CollectedHeap::rebuild_strong_code_roots() { 7254 RebuildStrongCodeRootClosure blob_cl(this); 7255 CodeCache::blobs_do(&blob_cl); 7256 }