1 /* 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc_implementation/shared/collectorCounters.hpp" 27 #include "gc_implementation/shared/gcPolicyCounters.hpp" 28 #include "gc_implementation/shared/spaceDecorator.hpp" 29 #include "memory/defNewGeneration.inline.hpp" 30 #include "memory/gcLocker.inline.hpp" 31 #include "memory/genCollectedHeap.hpp" 32 #include "memory/genOopClosures.inline.hpp" 33 #include "memory/generationSpec.hpp" 34 #include "memory/iterator.hpp" 35 #include "memory/referencePolicy.hpp" 36 #include "memory/space.inline.hpp" 37 #include "oops/instanceRefKlass.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "runtime/java.hpp" 40 #include "utilities/copy.hpp" 41 #include "utilities/stack.inline.hpp" 42 #ifdef TARGET_OS_FAMILY_linux 43 # include "thread_linux.inline.hpp" 44 #endif 45 #ifdef TARGET_OS_FAMILY_solaris 46 # include "thread_solaris.inline.hpp" 47 #endif 48 #ifdef TARGET_OS_FAMILY_windows 49 # include "thread_windows.inline.hpp" 50 #endif 51 #ifdef TARGET_OS_FAMILY_bsd 52 # include "thread_bsd.inline.hpp" 53 #endif 54 55 // 56 // DefNewGeneration functions. 57 58 // Methods of protected closure types. 59 60 DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* g) : _g(g) { 61 assert(g->level() == 0, "Optimized for youngest gen."); 62 } 63 void DefNewGeneration::IsAliveClosure::do_object(oop p) { 64 assert(false, "Do not call."); 65 } 66 bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) { 67 return (HeapWord*)p >= _g->reserved().end() || p->is_forwarded(); 68 } 69 70 DefNewGeneration::KeepAliveClosure:: 71 KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) { 72 GenRemSet* rs = GenCollectedHeap::heap()->rem_set(); 73 assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind."); 74 _rs = (CardTableRS*)rs; 75 } 76 77 void DefNewGeneration::KeepAliveClosure::do_oop(oop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); } 78 void DefNewGeneration::KeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); } 79 80 81 DefNewGeneration::FastKeepAliveClosure:: 82 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) : 83 DefNewGeneration::KeepAliveClosure(cl) { 84 _boundary = g->reserved().end(); 85 } 86 87 void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); } 88 void DefNewGeneration::FastKeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); } 89 90 DefNewGeneration::EvacuateFollowersClosure:: 91 EvacuateFollowersClosure(GenCollectedHeap* gch, int level, 92 ScanClosure* cur, ScanClosure* older) : 93 _gch(gch), _level(level), 94 _scan_cur_or_nonheap(cur), _scan_older(older) 95 {} 96 97 void DefNewGeneration::EvacuateFollowersClosure::do_void() { 98 do { 99 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap, 100 _scan_older); 101 } while (!_gch->no_allocs_since_save_marks(_level)); 102 } 103 104 DefNewGeneration::FastEvacuateFollowersClosure:: 105 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level, 106 DefNewGeneration* gen, 107 FastScanClosure* cur, FastScanClosure* older) : 108 _gch(gch), _level(level), _gen(gen), 109 _scan_cur_or_nonheap(cur), _scan_older(older) 110 {} 111 112 void DefNewGeneration::FastEvacuateFollowersClosure::do_void() { 113 do { 114 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap, 115 _scan_older); 116 } while (!_gch->no_allocs_since_save_marks(_level)); 117 guarantee(_gen->promo_failure_scan_is_complete(), "Failed to finish scan"); 118 } 119 120 ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) : 121 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier) 122 { 123 assert(_g->level() == 0, "Optimized for youngest generation"); 124 _boundary = _g->reserved().end(); 125 } 126 127 void ScanClosure::do_oop(oop* p) { ScanClosure::do_oop_work(p); } 128 void ScanClosure::do_oop(narrowOop* p) { ScanClosure::do_oop_work(p); } 129 130 FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) : 131 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier) 132 { 133 assert(_g->level() == 0, "Optimized for youngest generation"); 134 _boundary = _g->reserved().end(); 135 } 136 137 void FastScanClosure::do_oop(oop* p) { FastScanClosure::do_oop_work(p); } 138 void FastScanClosure::do_oop(narrowOop* p) { FastScanClosure::do_oop_work(p); } 139 140 ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) : 141 OopClosure(g->ref_processor()), _g(g) 142 { 143 assert(_g->level() == 0, "Optimized for youngest generation"); 144 _boundary = _g->reserved().end(); 145 } 146 147 void ScanWeakRefClosure::do_oop(oop* p) { ScanWeakRefClosure::do_oop_work(p); } 148 void ScanWeakRefClosure::do_oop(narrowOop* p) { ScanWeakRefClosure::do_oop_work(p); } 149 150 void FilteringClosure::do_oop(oop* p) { FilteringClosure::do_oop_work(p); } 151 void FilteringClosure::do_oop(narrowOop* p) { FilteringClosure::do_oop_work(p); } 152 153 DefNewGeneration::DefNewGeneration(ReservedSpace rs, 154 size_t initial_size, 155 int level, 156 const char* policy) 157 : Generation(rs, initial_size, level), 158 _promo_failure_drain_in_progress(false), 159 _should_allocate_from_space(false) 160 { 161 MemRegion cmr((HeapWord*)_virtual_space.low(), 162 (HeapWord*)_virtual_space.high()); 163 Universe::heap()->barrier_set()->resize_covered_region(cmr); 164 165 if (GenCollectedHeap::heap()->collector_policy()->has_soft_ended_eden()) { 166 _eden_space = new ConcEdenSpace(this); 167 } else { 168 _eden_space = new EdenSpace(this); 169 } 170 _from_space = new ContiguousSpace(); 171 _to_space = new ContiguousSpace(); 172 173 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL) 174 vm_exit_during_initialization("Could not allocate a new gen space"); 175 176 // Compute the maximum eden and survivor space sizes. These sizes 177 // are computed assuming the entire reserved space is committed. 178 // These values are exported as performance counters. 179 uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment(); 180 uintx size = _virtual_space.reserved_size(); 181 _max_survivor_size = compute_survivor_size(size, alignment); 182 _max_eden_size = size - (2*_max_survivor_size); 183 184 // allocate the performance counters 185 186 // Generation counters -- generation 0, 3 subspaces 187 _gen_counters = new GenerationCounters("new", 0, 3, &_virtual_space); 188 _gc_counters = new CollectorCounters(policy, 0); 189 190 _eden_counters = new CSpaceCounters("eden", 0, _max_eden_size, _eden_space, 191 _gen_counters); 192 _from_counters = new CSpaceCounters("s0", 1, _max_survivor_size, _from_space, 193 _gen_counters); 194 _to_counters = new CSpaceCounters("s1", 2, _max_survivor_size, _to_space, 195 _gen_counters); 196 197 compute_space_boundaries(0, SpaceDecorator::Clear, SpaceDecorator::Mangle); 198 update_counters(); 199 _next_gen = NULL; 200 _tenuring_threshold = MaxTenuringThreshold; 201 _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize; 202 } 203 204 void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size, 205 bool clear_space, 206 bool mangle_space) { 207 uintx alignment = 208 GenCollectedHeap::heap()->collector_policy()->min_alignment(); 209 210 // If the spaces are being cleared (only done at heap initialization 211 // currently), the survivor spaces need not be empty. 212 // Otherwise, no care is taken for used areas in the survivor spaces 213 // so check. 214 assert(clear_space || (to()->is_empty() && from()->is_empty()), 215 "Initialization of the survivor spaces assumes these are empty"); 216 217 // Compute sizes 218 uintx size = _virtual_space.committed_size(); 219 uintx survivor_size = compute_survivor_size(size, alignment); 220 uintx eden_size = size - (2*survivor_size); 221 assert(eden_size > 0 && survivor_size <= eden_size, "just checking"); 222 223 if (eden_size < minimum_eden_size) { 224 // May happen due to 64Kb rounding, if so adjust eden size back up 225 minimum_eden_size = align_size_up(minimum_eden_size, alignment); 226 uintx maximum_survivor_size = (size - minimum_eden_size) / 2; 227 uintx unaligned_survivor_size = 228 align_size_down(maximum_survivor_size, alignment); 229 survivor_size = MAX2(unaligned_survivor_size, alignment); 230 eden_size = size - (2*survivor_size); 231 assert(eden_size > 0 && survivor_size <= eden_size, "just checking"); 232 assert(eden_size >= minimum_eden_size, "just checking"); 233 } 234 235 char *eden_start = _virtual_space.low(); 236 char *from_start = eden_start + eden_size; 237 char *to_start = from_start + survivor_size; 238 char *to_end = to_start + survivor_size; 239 240 assert(to_end == _virtual_space.high(), "just checking"); 241 assert(Space::is_aligned((HeapWord*)eden_start), "checking alignment"); 242 assert(Space::is_aligned((HeapWord*)from_start), "checking alignment"); 243 assert(Space::is_aligned((HeapWord*)to_start), "checking alignment"); 244 245 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)from_start); 246 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)to_start); 247 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end); 248 249 // A minimum eden size implies that there is a part of eden that 250 // is being used and that affects the initialization of any 251 // newly formed eden. 252 bool live_in_eden = minimum_eden_size > 0; 253 254 // If not clearing the spaces, do some checking to verify that 255 // the space are already mangled. 256 if (!clear_space) { 257 // Must check mangling before the spaces are reshaped. Otherwise, 258 // the bottom or end of one space may have moved into another 259 // a failure of the check may not correctly indicate which space 260 // is not properly mangled. 261 if (ZapUnusedHeapArea) { 262 HeapWord* limit = (HeapWord*) _virtual_space.high(); 263 eden()->check_mangled_unused_area(limit); 264 from()->check_mangled_unused_area(limit); 265 to()->check_mangled_unused_area(limit); 266 } 267 } 268 269 // Reset the spaces for their new regions. 270 eden()->initialize(edenMR, 271 clear_space && !live_in_eden, 272 SpaceDecorator::Mangle); 273 // If clear_space and live_in_eden, we will not have cleared any 274 // portion of eden above its top. This can cause newly 275 // expanded space not to be mangled if using ZapUnusedHeapArea. 276 // We explicitly do such mangling here. 277 if (ZapUnusedHeapArea && clear_space && live_in_eden && mangle_space) { 278 eden()->mangle_unused_area(); 279 } 280 from()->initialize(fromMR, clear_space, mangle_space); 281 to()->initialize(toMR, clear_space, mangle_space); 282 283 // Set next compaction spaces. 284 eden()->set_next_compaction_space(from()); 285 // The to-space is normally empty before a compaction so need 286 // not be considered. The exception is during promotion 287 // failure handling when to-space can contain live objects. 288 from()->set_next_compaction_space(NULL); 289 } 290 291 void DefNewGeneration::swap_spaces() { 292 ContiguousSpace* s = from(); 293 _from_space = to(); 294 _to_space = s; 295 eden()->set_next_compaction_space(from()); 296 // The to-space is normally empty before a compaction so need 297 // not be considered. The exception is during promotion 298 // failure handling when to-space can contain live objects. 299 from()->set_next_compaction_space(NULL); 300 301 if (UsePerfData) { 302 CSpaceCounters* c = _from_counters; 303 _from_counters = _to_counters; 304 _to_counters = c; 305 } 306 } 307 308 bool DefNewGeneration::expand(size_t bytes) { 309 MutexLocker x(ExpandHeap_lock); 310 HeapWord* prev_high = (HeapWord*) _virtual_space.high(); 311 bool success = _virtual_space.expand_by(bytes); 312 if (success && ZapUnusedHeapArea) { 313 // Mangle newly committed space immediately because it 314 // can be done here more simply that after the new 315 // spaces have been computed. 316 HeapWord* new_high = (HeapWord*) _virtual_space.high(); 317 MemRegion mangle_region(prev_high, new_high); 318 SpaceMangler::mangle_region(mangle_region); 319 } 320 321 // Do not attempt an expand-to-the reserve size. The 322 // request should properly observe the maximum size of 323 // the generation so an expand-to-reserve should be 324 // unnecessary. Also a second call to expand-to-reserve 325 // value potentially can cause an undue expansion. 326 // For example if the first expand fail for unknown reasons, 327 // but the second succeeds and expands the heap to its maximum 328 // value. 329 if (GC_locker::is_active()) { 330 if (PrintGC && Verbose) { 331 gclog_or_tty->print_cr("Garbage collection disabled, " 332 "expanded heap instead"); 333 } 334 } 335 336 return success; 337 } 338 339 340 void DefNewGeneration::compute_new_size() { 341 // This is called after a gc that includes the following generation 342 // (which is required to exist.) So from-space will normally be empty. 343 // Note that we check both spaces, since if scavenge failed they revert roles. 344 // If not we bail out (otherwise we would have to relocate the objects) 345 if (!from()->is_empty() || !to()->is_empty()) { 346 return; 347 } 348 349 int next_level = level() + 1; 350 GenCollectedHeap* gch = GenCollectedHeap::heap(); 351 assert(next_level < gch->_n_gens, 352 "DefNewGeneration cannot be an oldest gen"); 353 354 Generation* next_gen = gch->_gens[next_level]; 355 size_t old_size = next_gen->capacity(); 356 size_t new_size_before = _virtual_space.committed_size(); 357 size_t min_new_size = spec()->init_size(); 358 size_t max_new_size = reserved().byte_size(); 359 assert(min_new_size <= new_size_before && 360 new_size_before <= max_new_size, 361 "just checking"); 362 // All space sizes must be multiples of Generation::GenGrain. 363 size_t alignment = Generation::GenGrain; 364 365 // Compute desired new generation size based on NewRatio and 366 // NewSizeThreadIncrease 367 size_t desired_new_size = old_size/NewRatio; 368 int threads_count = Threads::number_of_non_daemon_threads(); 369 size_t thread_increase_size = threads_count * NewSizeThreadIncrease; 370 desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment); 371 372 // Adjust new generation size 373 desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size); 374 assert(desired_new_size <= max_new_size, "just checking"); 375 376 bool changed = false; 377 if (desired_new_size > new_size_before) { 378 size_t change = desired_new_size - new_size_before; 379 assert(change % alignment == 0, "just checking"); 380 if (expand(change)) { 381 changed = true; 382 } 383 // If the heap failed to expand to the desired size, 384 // "changed" will be false. If the expansion failed 385 // (and at this point it was expected to succeed), 386 // ignore the failure (leaving "changed" as false). 387 } 388 if (desired_new_size < new_size_before && eden()->is_empty()) { 389 // bail out of shrinking if objects in eden 390 size_t change = new_size_before - desired_new_size; 391 assert(change % alignment == 0, "just checking"); 392 _virtual_space.shrink_by(change); 393 changed = true; 394 } 395 if (changed) { 396 // The spaces have already been mangled at this point but 397 // may not have been cleared (set top = bottom) and should be. 398 // Mangling was done when the heap was being expanded. 399 compute_space_boundaries(eden()->used(), 400 SpaceDecorator::Clear, 401 SpaceDecorator::DontMangle); 402 MemRegion cmr((HeapWord*)_virtual_space.low(), 403 (HeapWord*)_virtual_space.high()); 404 Universe::heap()->barrier_set()->resize_covered_region(cmr); 405 if (Verbose && PrintGC) { 406 size_t new_size_after = _virtual_space.committed_size(); 407 size_t eden_size_after = eden()->capacity(); 408 size_t survivor_size_after = from()->capacity(); 409 gclog_or_tty->print("New generation size " SIZE_FORMAT "K->" 410 SIZE_FORMAT "K [eden=" 411 SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]", 412 new_size_before/K, new_size_after/K, 413 eden_size_after/K, survivor_size_after/K); 414 if (WizardMode) { 415 gclog_or_tty->print("[allowed " SIZE_FORMAT "K extra for %d threads]", 416 thread_increase_size/K, threads_count); 417 } 418 gclog_or_tty->cr(); 419 } 420 } 421 } 422 423 void DefNewGeneration::object_iterate_since_last_GC(ObjectClosure* cl) { 424 // $$$ This may be wrong in case of "scavenge failure"? 425 eden()->object_iterate(cl); 426 } 427 428 void DefNewGeneration::younger_refs_iterate(OopsInGenClosure* cl) { 429 assert(false, "NYI -- are you sure you want to call this?"); 430 } 431 432 433 size_t DefNewGeneration::capacity() const { 434 return eden()->capacity() 435 + from()->capacity(); // to() is only used during scavenge 436 } 437 438 439 size_t DefNewGeneration::used() const { 440 return eden()->used() 441 + from()->used(); // to() is only used during scavenge 442 } 443 444 445 size_t DefNewGeneration::free() const { 446 return eden()->free() 447 + from()->free(); // to() is only used during scavenge 448 } 449 450 size_t DefNewGeneration::max_capacity() const { 451 const size_t alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment(); 452 const size_t reserved_bytes = reserved().byte_size(); 453 return reserved_bytes - compute_survivor_size(reserved_bytes, alignment); 454 } 455 456 size_t DefNewGeneration::unsafe_max_alloc_nogc() const { 457 return eden()->free(); 458 } 459 460 size_t DefNewGeneration::capacity_before_gc() const { 461 return eden()->capacity(); 462 } 463 464 size_t DefNewGeneration::contiguous_available() const { 465 return eden()->free(); 466 } 467 468 469 HeapWord** DefNewGeneration::top_addr() const { return eden()->top_addr(); } 470 HeapWord** DefNewGeneration::end_addr() const { return eden()->end_addr(); } 471 472 void DefNewGeneration::object_iterate(ObjectClosure* blk) { 473 eden()->object_iterate(blk); 474 from()->object_iterate(blk); 475 } 476 477 478 void DefNewGeneration::space_iterate(SpaceClosure* blk, 479 bool usedOnly) { 480 blk->do_space(eden()); 481 blk->do_space(from()); 482 blk->do_space(to()); 483 } 484 485 // The last collection bailed out, we are running out of heap space, 486 // so we try to allocate the from-space, too. 487 HeapWord* DefNewGeneration::allocate_from_space(size_t size) { 488 HeapWord* result = NULL; 489 if (Verbose && PrintGCDetails) { 490 gclog_or_tty->print("DefNewGeneration::allocate_from_space(%u):" 491 " will_fail: %s" 492 " heap_lock: %s" 493 " free: " SIZE_FORMAT, 494 size, 495 GenCollectedHeap::heap()->incremental_collection_will_fail(false /* don't consult_young */) ? 496 "true" : "false", 497 Heap_lock->is_locked() ? "locked" : "unlocked", 498 from()->free()); 499 } 500 if (should_allocate_from_space() || GC_locker::is_active_and_needs_gc()) { 501 if (Heap_lock->owned_by_self() || 502 (SafepointSynchronize::is_at_safepoint() && 503 Thread::current()->is_VM_thread())) { 504 // If the Heap_lock is not locked by this thread, this will be called 505 // again later with the Heap_lock held. 506 result = from()->allocate(size); 507 } else if (PrintGC && Verbose) { 508 gclog_or_tty->print_cr(" Heap_lock is not owned by self"); 509 } 510 } else if (PrintGC && Verbose) { 511 gclog_or_tty->print_cr(" should_allocate_from_space: NOT"); 512 } 513 if (PrintGC && Verbose) { 514 gclog_or_tty->print_cr(" returns %s", result == NULL ? "NULL" : "object"); 515 } 516 return result; 517 } 518 519 HeapWord* DefNewGeneration::expand_and_allocate(size_t size, 520 bool is_tlab, 521 bool parallel) { 522 // We don't attempt to expand the young generation (but perhaps we should.) 523 return allocate(size, is_tlab); 524 } 525 526 527 void DefNewGeneration::collect(bool full, 528 bool clear_all_soft_refs, 529 size_t size, 530 bool is_tlab) { 531 assert(full || size > 0, "otherwise we don't want to collect"); 532 GenCollectedHeap* gch = GenCollectedHeap::heap(); 533 _next_gen = gch->next_gen(this); 534 assert(_next_gen != NULL, 535 "This must be the youngest gen, and not the only gen"); 536 537 // If the next generation is too full to accomodate promotion 538 // from this generation, pass on collection; let the next generation 539 // do it. 540 if (!collection_attempt_is_safe()) { 541 if (Verbose && PrintGCDetails) { 542 gclog_or_tty->print(" :: Collection attempt not safe :: "); 543 } 544 gch->set_incremental_collection_failed(); // Slight lie: we did not even attempt one 545 return; 546 } 547 assert(to()->is_empty(), "Else not collection_attempt_is_safe"); 548 549 init_assuming_no_promotion_failure(); 550 551 TraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, gclog_or_tty); 552 // Capture heap used before collection (for printing). 553 size_t gch_prev_used = gch->used(); 554 555 SpecializationStats::clear(); 556 557 // These can be shared for all code paths 558 IsAliveClosure is_alive(this); 559 ScanWeakRefClosure scan_weak_ref(this); 560 561 age_table()->clear(); 562 to()->clear(SpaceDecorator::Mangle); 563 564 gch->rem_set()->prepare_for_younger_refs_iterate(false); 565 566 assert(gch->no_allocs_since_save_marks(0), 567 "save marks have not been newly set."); 568 569 // Not very pretty. 570 CollectorPolicy* cp = gch->collector_policy(); 571 572 FastScanClosure fsc_with_no_gc_barrier(this, false); 573 FastScanClosure fsc_with_gc_barrier(this, true); 574 575 set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier); 576 FastEvacuateFollowersClosure evacuate_followers(gch, _level, this, 577 &fsc_with_no_gc_barrier, 578 &fsc_with_gc_barrier); 579 580 assert(gch->no_allocs_since_save_marks(0), 581 "save marks have not been newly set."); 582 583 gch->gen_process_strong_roots(_level, 584 true, // Process younger gens, if any, 585 // as strong roots. 586 true, // activate StrongRootsScope 587 false, // not collecting perm generation. 588 SharedHeap::SO_AllClasses, 589 &fsc_with_no_gc_barrier, 590 true, // walk *all* scavengable nmethods 591 &fsc_with_gc_barrier); 592 593 // "evacuate followers". 594 evacuate_followers.do_void(); 595 596 FastKeepAliveClosure keep_alive(this, &scan_weak_ref); 597 ReferenceProcessor* rp = ref_processor(); 598 rp->setup_policy(clear_all_soft_refs); 599 rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers, 600 NULL); 601 if (!promotion_failed()) { 602 // Swap the survivor spaces. 603 eden()->clear(SpaceDecorator::Mangle); 604 from()->clear(SpaceDecorator::Mangle); 605 if (ZapUnusedHeapArea) { 606 // This is now done here because of the piece-meal mangling which 607 // can check for valid mangling at intermediate points in the 608 // collection(s). When a minor collection fails to collect 609 // sufficient space resizing of the young generation can occur 610 // an redistribute the spaces in the young generation. Mangle 611 // here so that unzapped regions don't get distributed to 612 // other spaces. 613 to()->mangle_unused_area(); 614 } 615 swap_spaces(); 616 617 assert(to()->is_empty(), "to space should be empty now"); 618 619 // Set the desired survivor size to half the real survivor space 620 _tenuring_threshold = 621 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); 622 623 // A successful scavenge should restart the GC time limit count which is 624 // for full GC's. 625 AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy(); 626 size_policy->reset_gc_overhead_limit_count(); 627 if (PrintGC && !PrintGCDetails) { 628 gch->print_heap_change(gch_prev_used); 629 } 630 assert(!gch->incremental_collection_failed(), "Should be clear"); 631 } else { 632 assert(_promo_failure_scan_stack.is_empty(), "post condition"); 633 _promo_failure_scan_stack.clear(true); // Clear cached segments. 634 635 remove_forwarding_pointers(); 636 if (PrintGCDetails) { 637 gclog_or_tty->print(" (promotion failed) "); 638 } 639 // Add to-space to the list of space to compact 640 // when a promotion failure has occurred. In that 641 // case there can be live objects in to-space 642 // as a result of a partial evacuation of eden 643 // and from-space. 644 swap_spaces(); // For uniformity wrt ParNewGeneration. 645 from()->set_next_compaction_space(to()); 646 gch->set_incremental_collection_failed(); 647 648 // Inform the next generation that a promotion failure occurred. 649 _next_gen->promotion_failure_occurred(); 650 651 // Reset the PromotionFailureALot counters. 652 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) 653 } 654 // set new iteration safe limit for the survivor spaces 655 from()->set_concurrent_iteration_safe_limit(from()->top()); 656 to()->set_concurrent_iteration_safe_limit(to()->top()); 657 SpecializationStats::print(); 658 659 // We need to use a monotonically non-deccreasing time in ms 660 // or we will see time-warp warnings and os::javaTimeMillis() 661 // does not guarantee monotonicity. 662 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 663 update_time_of_last_gc(now); 664 } 665 666 class RemoveForwardPointerClosure: public ObjectClosure { 667 public: 668 void do_object(oop obj) { 669 obj->init_mark(); 670 } 671 }; 672 673 void DefNewGeneration::init_assuming_no_promotion_failure() { 674 _promotion_failed = false; 675 from()->set_next_compaction_space(NULL); 676 } 677 678 void DefNewGeneration::remove_forwarding_pointers() { 679 RemoveForwardPointerClosure rspc; 680 eden()->object_iterate(&rspc); 681 from()->object_iterate(&rspc); 682 683 // Now restore saved marks, if any. 684 assert(_objs_with_preserved_marks.size() == _preserved_marks_of_objs.size(), 685 "should be the same"); 686 while (!_objs_with_preserved_marks.is_empty()) { 687 oop obj = _objs_with_preserved_marks.pop(); 688 markOop m = _preserved_marks_of_objs.pop(); 689 obj->set_mark(m); 690 } 691 _objs_with_preserved_marks.clear(true); 692 _preserved_marks_of_objs.clear(true); 693 } 694 695 void DefNewGeneration::preserve_mark(oop obj, markOop m) { 696 assert(promotion_failed() && m->must_be_preserved_for_promotion_failure(obj), 697 "Oversaving!"); 698 _objs_with_preserved_marks.push(obj); 699 _preserved_marks_of_objs.push(m); 700 } 701 702 void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { 703 if (m->must_be_preserved_for_promotion_failure(obj)) { 704 preserve_mark(obj, m); 705 } 706 } 707 708 void DefNewGeneration::handle_promotion_failure(oop old) { 709 if (PrintPromotionFailure && !_promotion_failed) { 710 gclog_or_tty->print(" (promotion failure size = " SIZE_FORMAT ") ", 711 old->size()); 712 } 713 _promotion_failed = true; 714 preserve_mark_if_necessary(old, old->mark()); 715 // forward to self 716 old->forward_to(old); 717 718 _promo_failure_scan_stack.push(old); 719 720 if (!_promo_failure_drain_in_progress) { 721 // prevent recursion in copy_to_survivor_space() 722 _promo_failure_drain_in_progress = true; 723 drain_promo_failure_scan_stack(); 724 _promo_failure_drain_in_progress = false; 725 } 726 } 727 728 oop DefNewGeneration::copy_to_survivor_space(oop old) { 729 assert(is_in_reserved(old) && !old->is_forwarded(), 730 "shouldn't be scavenging this oop"); 731 size_t s = old->size(); 732 oop obj = NULL; 733 734 // Try allocating obj in to-space (unless too old) 735 if (old->age() < tenuring_threshold()) { 736 obj = (oop) to()->allocate(s); 737 } 738 739 // Otherwise try allocating obj tenured 740 if (obj == NULL) { 741 obj = _next_gen->promote(old, s); 742 if (obj == NULL) { 743 handle_promotion_failure(old); 744 return old; 745 } 746 } else { 747 // Prefetch beyond obj 748 const intx interval = PrefetchCopyIntervalInBytes; 749 Prefetch::write(obj, interval); 750 751 // Copy obj 752 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)obj, s); 753 754 // Increment age if obj still in new generation 755 obj->incr_age(); 756 age_table()->add(obj, s); 757 } 758 759 // Done, insert forward pointer to obj in this header 760 old->forward_to(obj); 761 762 return obj; 763 } 764 765 void DefNewGeneration::drain_promo_failure_scan_stack() { 766 while (!_promo_failure_scan_stack.is_empty()) { 767 oop obj = _promo_failure_scan_stack.pop(); 768 obj->oop_iterate(_promo_failure_scan_stack_closure); 769 } 770 } 771 772 void DefNewGeneration::save_marks() { 773 eden()->set_saved_mark(); 774 to()->set_saved_mark(); 775 from()->set_saved_mark(); 776 } 777 778 779 void DefNewGeneration::reset_saved_marks() { 780 eden()->reset_saved_mark(); 781 to()->reset_saved_mark(); 782 from()->reset_saved_mark(); 783 } 784 785 786 bool DefNewGeneration::no_allocs_since_save_marks() { 787 assert(eden()->saved_mark_at_top(), "Violated spec - alloc in eden"); 788 assert(from()->saved_mark_at_top(), "Violated spec - alloc in from"); 789 return to()->saved_mark_at_top(); 790 } 791 792 #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ 793 \ 794 void DefNewGeneration:: \ 795 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ 796 cl->set_generation(this); \ 797 eden()->oop_since_save_marks_iterate##nv_suffix(cl); \ 798 to()->oop_since_save_marks_iterate##nv_suffix(cl); \ 799 from()->oop_since_save_marks_iterate##nv_suffix(cl); \ 800 cl->reset_generation(); \ 801 save_marks(); \ 802 } 803 804 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN) 805 806 #undef DefNew_SINCE_SAVE_MARKS_DEFN 807 808 void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor, 809 size_t max_alloc_words) { 810 if (requestor == this || _promotion_failed) return; 811 assert(requestor->level() > level(), "DefNewGeneration must be youngest"); 812 813 /* $$$ Assert this? "trace" is a "MarkSweep" function so that's not appropriate. 814 if (to_space->top() > to_space->bottom()) { 815 trace("to_space not empty when contribute_scratch called"); 816 } 817 */ 818 819 ContiguousSpace* to_space = to(); 820 assert(to_space->end() >= to_space->top(), "pointers out of order"); 821 size_t free_words = pointer_delta(to_space->end(), to_space->top()); 822 if (free_words >= MinFreeScratchWords) { 823 ScratchBlock* sb = (ScratchBlock*)to_space->top(); 824 sb->num_words = free_words; 825 sb->next = list; 826 list = sb; 827 } 828 } 829 830 void DefNewGeneration::reset_scratch() { 831 // If contributing scratch in to_space, mangle all of 832 // to_space if ZapUnusedHeapArea. This is needed because 833 // top is not maintained while using to-space as scratch. 834 if (ZapUnusedHeapArea) { 835 to()->mangle_unused_area_complete(); 836 } 837 } 838 839 bool DefNewGeneration::collection_attempt_is_safe() { 840 if (!to()->is_empty()) { 841 if (Verbose && PrintGCDetails) { 842 gclog_or_tty->print(" :: to is not empty :: "); 843 } 844 return false; 845 } 846 if (_next_gen == NULL) { 847 GenCollectedHeap* gch = GenCollectedHeap::heap(); 848 _next_gen = gch->next_gen(this); 849 assert(_next_gen != NULL, 850 "This must be the youngest gen, and not the only gen"); 851 } 852 return _next_gen->promotion_attempt_is_safe(used()); 853 } 854 855 void DefNewGeneration::gc_epilogue(bool full) { 856 DEBUG_ONLY(static bool seen_incremental_collection_failed = false;) 857 858 assert(!GC_locker::is_active(), "We should not be executing here"); 859 // Check if the heap is approaching full after a collection has 860 // been done. Generally the young generation is empty at 861 // a minimum at the end of a collection. If it is not, then 862 // the heap is approaching full. 863 GenCollectedHeap* gch = GenCollectedHeap::heap(); 864 if (full) { 865 DEBUG_ONLY(seen_incremental_collection_failed = false;) 866 if (!collection_attempt_is_safe() && !_eden_space->is_empty()) { 867 if (Verbose && PrintGCDetails) { 868 gclog_or_tty->print("DefNewEpilogue: cause(%s), full, not safe, set_failed, set_alloc_from, clear_seen", 869 GCCause::to_string(gch->gc_cause())); 870 } 871 gch->set_incremental_collection_failed(); // Slight lie: a full gc left us in that state 872 set_should_allocate_from_space(); // we seem to be running out of space 873 } else { 874 if (Verbose && PrintGCDetails) { 875 gclog_or_tty->print("DefNewEpilogue: cause(%s), full, safe, clear_failed, clear_alloc_from, clear_seen", 876 GCCause::to_string(gch->gc_cause())); 877 } 878 gch->clear_incremental_collection_failed(); // We just did a full collection 879 clear_should_allocate_from_space(); // if set 880 } 881 } else { 882 #ifdef ASSERT 883 // It is possible that incremental_collection_failed() == true 884 // here, because an attempted scavenge did not succeed. The policy 885 // is normally expected to cause a full collection which should 886 // clear that condition, so we should not be here twice in a row 887 // with incremental_collection_failed() == true without having done 888 // a full collection in between. 889 if (!seen_incremental_collection_failed && 890 gch->incremental_collection_failed()) { 891 if (Verbose && PrintGCDetails) { 892 gclog_or_tty->print("DefNewEpilogue: cause(%s), not full, not_seen_failed, failed, set_seen_failed", 893 GCCause::to_string(gch->gc_cause())); 894 } 895 seen_incremental_collection_failed = true; 896 } else if (seen_incremental_collection_failed) { 897 if (Verbose && PrintGCDetails) { 898 gclog_or_tty->print("DefNewEpilogue: cause(%s), not full, seen_failed, will_clear_seen_failed", 899 GCCause::to_string(gch->gc_cause())); 900 } 901 assert(gch->gc_cause() == GCCause::_scavenge_alot || 902 (gch->gc_cause() == GCCause::_java_lang_system_gc && UseConcMarkSweepGC && ExplicitGCInvokesConcurrent) || 903 !gch->incremental_collection_failed(), 904 "Twice in a row"); 905 seen_incremental_collection_failed = false; 906 } 907 #endif // ASSERT 908 } 909 910 if (ZapUnusedHeapArea) { 911 eden()->check_mangled_unused_area_complete(); 912 from()->check_mangled_unused_area_complete(); 913 to()->check_mangled_unused_area_complete(); 914 } 915 916 if (!CleanChunkPoolAsync) { 917 Chunk::clean_chunk_pool(); 918 } 919 920 // update the generation and space performance counters 921 update_counters(); 922 gch->collector_policy()->counters()->update_counters(); 923 } 924 925 void DefNewGeneration::record_spaces_top() { 926 assert(ZapUnusedHeapArea, "Not mangling unused space"); 927 eden()->set_top_for_allocations(); 928 to()->set_top_for_allocations(); 929 from()->set_top_for_allocations(); 930 } 931 932 933 void DefNewGeneration::update_counters() { 934 if (UsePerfData) { 935 _eden_counters->update_all(); 936 _from_counters->update_all(); 937 _to_counters->update_all(); 938 _gen_counters->update_all(); 939 } 940 } 941 942 void DefNewGeneration::verify() { 943 eden()->verify(); 944 from()->verify(); 945 to()->verify(); 946 } 947 948 void DefNewGeneration::print_on(outputStream* st) const { 949 Generation::print_on(st); 950 st->print(" eden"); 951 eden()->print_on(st); 952 st->print(" from"); 953 from()->print_on(st); 954 st->print(" to "); 955 to()->print_on(st); 956 } 957 958 959 const char* DefNewGeneration::name() const { 960 return "def new generation"; 961 } 962 963 // Moved from inline file as they are not called inline 964 CompactibleSpace* DefNewGeneration::first_compaction_space() const { 965 return eden(); 966 } 967 968 HeapWord* DefNewGeneration::allocate(size_t word_size, 969 bool is_tlab) { 970 // This is the slow-path allocation for the DefNewGeneration. 971 // Most allocations are fast-path in compiled code. 972 // We try to allocate from the eden. If that works, we are happy. 973 // Note that since DefNewGeneration supports lock-free allocation, we 974 // have to use it here, as well. 975 HeapWord* result = eden()->par_allocate(word_size); 976 if (result != NULL) { 977 return result; 978 } 979 do { 980 HeapWord* old_limit = eden()->soft_end(); 981 if (old_limit < eden()->end()) { 982 // Tell the next generation we reached a limit. 983 HeapWord* new_limit = 984 next_gen()->allocation_limit_reached(eden(), eden()->top(), word_size); 985 if (new_limit != NULL) { 986 Atomic::cmpxchg_ptr(new_limit, eden()->soft_end_addr(), old_limit); 987 } else { 988 assert(eden()->soft_end() == eden()->end(), 989 "invalid state after allocation_limit_reached returned null"); 990 } 991 } else { 992 // The allocation failed and the soft limit is equal to the hard limit, 993 // there are no reasons to do an attempt to allocate 994 assert(old_limit == eden()->end(), "sanity check"); 995 break; 996 } 997 // Try to allocate until succeeded or the soft limit can't be adjusted 998 result = eden()->par_allocate(word_size); 999 } while (result == NULL); 1000 1001 // If the eden is full and the last collection bailed out, we are running 1002 // out of heap space, and we try to allocate the from-space, too. 1003 // allocate_from_space can't be inlined because that would introduce a 1004 // circular dependency at compile time. 1005 if (result == NULL) { 1006 result = allocate_from_space(word_size); 1007 } 1008 return result; 1009 } 1010 1011 HeapWord* DefNewGeneration::par_allocate(size_t word_size, 1012 bool is_tlab) { 1013 return eden()->par_allocate(word_size); 1014 } 1015 1016 void DefNewGeneration::gc_prologue(bool full) { 1017 // Ensure that _end and _soft_end are the same in eden space. 1018 eden()->set_soft_end(eden()->end()); 1019 } 1020 1021 size_t DefNewGeneration::tlab_capacity() const { 1022 return eden()->capacity(); 1023 } 1024 1025 size_t DefNewGeneration::unsafe_max_tlab_alloc() const { 1026 return unsafe_max_alloc_nogc(); 1027 }