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src/share/vm/gc/serial/defNewGeneration.cpp

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  41 #include "gc/shared/strongRootsScope.hpp"
  42 #include "memory/iterator.hpp"
  43 #include "oops/instanceRefKlass.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "runtime/atomic.inline.hpp"
  46 #include "runtime/java.hpp"
  47 #include "runtime/prefetch.inline.hpp"
  48 #include "runtime/thread.inline.hpp"
  49 #include "utilities/copy.hpp"
  50 #include "utilities/globalDefinitions.hpp"
  51 #include "utilities/stack.inline.hpp"
  52 #if INCLUDE_ALL_GCS
  53 #include "gc/cms/parOopClosures.hpp"
  54 #endif
  55 
  56 //
  57 // DefNewGeneration functions.
  58 
  59 // Methods of protected closure types.
  60 
  61 DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* g) : _g(g) {
  62   assert(g->level() == 0, "Optimized for youngest gen.");

  63 }

  64 bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) {
  65   return (HeapWord*)p >= _g->reserved().end() || p->is_forwarded();
  66 }
  67 
  68 DefNewGeneration::KeepAliveClosure::
  69 KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) {
  70   GenRemSet* rs = GenCollectedHeap::heap()->rem_set();
  71   _rs = (CardTableRS*)rs;
  72 }
  73 
  74 void DefNewGeneration::KeepAliveClosure::do_oop(oop* p)       { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
  75 void DefNewGeneration::KeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
  76 
  77 
  78 DefNewGeneration::FastKeepAliveClosure::
  79 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) :
  80   DefNewGeneration::KeepAliveClosure(cl) {
  81   _boundary = g->reserved().end();
  82 }
  83 
  84 void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p)       { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
  85 void DefNewGeneration::FastKeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
  86 
  87 DefNewGeneration::EvacuateFollowersClosure::
  88 EvacuateFollowersClosure(GenCollectedHeap* gch, int level,
  89                          ScanClosure* cur, ScanClosure* older) :
  90   _gch(gch), _level(level),
  91   _scan_cur_or_nonheap(cur), _scan_older(older)
  92 {}
  93 
  94 void DefNewGeneration::EvacuateFollowersClosure::do_void() {
  95   do {
  96     _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
  97                                        _scan_older);
  98   } while (!_gch->no_allocs_since_save_marks(_level));
  99 }
 100 
 101 DefNewGeneration::FastEvacuateFollowersClosure::
 102 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level,
 103                              DefNewGeneration* gen,
 104                              FastScanClosure* cur, FastScanClosure* older) :
 105   _gch(gch), _level(level), _gen(gen),
 106   _scan_cur_or_nonheap(cur), _scan_older(older)
 107 {}


 108 
 109 void DefNewGeneration::FastEvacuateFollowersClosure::do_void() {
 110   do {
 111     _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
 112                                        _scan_older);
 113   } while (!_gch->no_allocs_since_save_marks(_level));
 114   guarantee(_gen->promo_failure_scan_is_complete(), "Failed to finish scan");
 115 }
 116 
 117 ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) :
 118     OopsInKlassOrGenClosure(g), _g(g), _gc_barrier(gc_barrier)
 119 {
 120   assert(_g->level() == 0, "Optimized for youngest generation");
 121   _boundary = _g->reserved().end();
 122 }
 123 
 124 void ScanClosure::do_oop(oop* p)       { ScanClosure::do_oop_work(p); }
 125 void ScanClosure::do_oop(narrowOop* p) { ScanClosure::do_oop_work(p); }
 126 
 127 FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) :
 128     OopsInKlassOrGenClosure(g), _g(g), _gc_barrier(gc_barrier)
 129 {
 130   assert(_g->level() == 0, "Optimized for youngest generation");
 131   _boundary = _g->reserved().end();
 132 }
 133 
 134 void FastScanClosure::do_oop(oop* p)       { FastScanClosure::do_oop_work(p); }
 135 void FastScanClosure::do_oop(narrowOop* p) { FastScanClosure::do_oop_work(p); }
 136 
 137 void KlassScanClosure::do_klass(Klass* klass) {
 138 #ifndef PRODUCT
 139   if (TraceScavenge) {
 140     ResourceMark rm;
 141     gclog_or_tty->print_cr("KlassScanClosure::do_klass " PTR_FORMAT ", %s, dirty: %s",
 142                            p2i(klass),
 143                            klass->external_name(),
 144                            klass->has_modified_oops() ? "true" : "false");
 145   }
 146 #endif
 147 
 148   // If the klass has not been dirtied we know that there's
 149   // no references into  the young gen and we can skip it.
 150   if (klass->has_modified_oops()) {
 151     if (_accumulate_modified_oops) {
 152       klass->accumulate_modified_oops();
 153     }
 154 
 155     // Clear this state since we're going to scavenge all the metadata.
 156     klass->clear_modified_oops();
 157 
 158     // Tell the closure which Klass is being scanned so that it can be dirtied
 159     // if oops are left pointing into the young gen.
 160     _scavenge_closure->set_scanned_klass(klass);
 161 
 162     klass->oops_do(_scavenge_closure);
 163 
 164     _scavenge_closure->set_scanned_klass(NULL);
 165   }
 166 }
 167 
 168 ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) :
 169   _g(g)
 170 {
 171   assert(_g->level() == 0, "Optimized for youngest generation");
 172   _boundary = _g->reserved().end();
 173 }
 174 
 175 void ScanWeakRefClosure::do_oop(oop* p)       { ScanWeakRefClosure::do_oop_work(p); }
 176 void ScanWeakRefClosure::do_oop(narrowOop* p) { ScanWeakRefClosure::do_oop_work(p); }
 177 
 178 void FilteringClosure::do_oop(oop* p)       { FilteringClosure::do_oop_work(p); }
 179 void FilteringClosure::do_oop(narrowOop* p) { FilteringClosure::do_oop_work(p); }
 180 
 181 KlassScanClosure::KlassScanClosure(OopsInKlassOrGenClosure* scavenge_closure,
 182                                    KlassRemSet* klass_rem_set)
 183     : _scavenge_closure(scavenge_closure),
 184       _accumulate_modified_oops(klass_rem_set->accumulate_modified_oops()) {}
 185 
 186 
 187 DefNewGeneration::DefNewGeneration(ReservedSpace rs,
 188                                    size_t initial_size,
 189                                    int level,
 190                                    const char* policy)
 191   : Generation(rs, initial_size, level),
 192     _promo_failure_drain_in_progress(false),
 193     _should_allocate_from_space(false)
 194 {
 195   MemRegion cmr((HeapWord*)_virtual_space.low(),
 196                 (HeapWord*)_virtual_space.high());
 197   GenCollectedHeap* gch = GenCollectedHeap::heap();
 198 
 199   gch->barrier_set()->resize_covered_region(cmr);
 200 
 201   _eden_space = new ContiguousSpace();
 202   _from_space = new ContiguousSpace();
 203   _to_space   = new ContiguousSpace();
 204 
 205   if (_eden_space == NULL || _from_space == NULL || _to_space == NULL)
 206     vm_exit_during_initialization("Could not allocate a new gen space");
 207 
 208   // Compute the maximum eden and survivor space sizes. These sizes
 209   // are computed assuming the entire reserved space is committed.
 210   // These values are exported as performance counters.
 211   uintx alignment = gch->collector_policy()->space_alignment();


 355   }
 356 
 357   // Do not attempt an expand-to-the reserve size.  The
 358   // request should properly observe the maximum size of
 359   // the generation so an expand-to-reserve should be
 360   // unnecessary.  Also a second call to expand-to-reserve
 361   // value potentially can cause an undue expansion.
 362   // For example if the first expand fail for unknown reasons,
 363   // but the second succeeds and expands the heap to its maximum
 364   // value.
 365   if (GC_locker::is_active()) {
 366     if (PrintGC && Verbose) {
 367       gclog_or_tty->print_cr("Garbage collection disabled, "
 368         "expanded heap instead");
 369     }
 370   }
 371 
 372   return success;
 373 }
 374 
 375 
 376 void DefNewGeneration::compute_new_size() {
 377   // This is called after a gc that includes the following generation
 378   // (which is required to exist.)  So from-space will normally be empty.
 379   // Note that we check both spaces, since if scavenge failed they revert roles.
 380   // If not we bail out (otherwise we would have to relocate the objects)
 381   if (!from()->is_empty() || !to()->is_empty()) {
 382     return;
 383   }
 384 
 385   int next_level = level() + 1;
 386   GenCollectedHeap* gch = GenCollectedHeap::heap();
 387   assert(next_level == 1, "DefNewGeneration must be a young gen");
 388 
 389   Generation* old_gen = gch->old_gen();
 390   size_t old_size = old_gen->capacity();
 391   size_t new_size_before = _virtual_space.committed_size();
 392   size_t min_new_size = spec()->init_size();
 393   size_t max_new_size = reserved().byte_size();
 394   assert(min_new_size <= new_size_before &&
 395          new_size_before <= max_new_size,
 396          "just checking");
 397   // All space sizes must be multiples of Generation::GenGrain.
 398   size_t alignment = Generation::GenGrain;
 399 
 400   // Compute desired new generation size based on NewRatio and
 401   // NewSizeThreadIncrease
 402   size_t desired_new_size = old_size/NewRatio;
 403   int threads_count = Threads::number_of_non_daemon_threads();
 404   size_t thread_increase_size = threads_count * NewSizeThreadIncrease;
 405   desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment);
 406 
 407   // Adjust new generation size
 408   desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size);
 409   assert(desired_new_size <= max_new_size, "just checking");
 410 


 586   }
 587   assert(to()->is_empty(), "Else not collection_attempt_is_safe");
 588 
 589   init_assuming_no_promotion_failure();
 590 
 591   GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, gc_tracer.gc_id());
 592   // Capture heap used before collection (for printing).
 593   size_t gch_prev_used = gch->used();
 594 
 595   gch->trace_heap_before_gc(&gc_tracer);
 596 
 597   // These can be shared for all code paths
 598   IsAliveClosure is_alive(this);
 599   ScanWeakRefClosure scan_weak_ref(this);
 600 
 601   age_table()->clear();
 602   to()->clear(SpaceDecorator::Mangle);
 603 
 604   gch->rem_set()->prepare_for_younger_refs_iterate(false);
 605 
 606   assert(gch->no_allocs_since_save_marks(0),
 607          "save marks have not been newly set.");
 608 
 609   // Not very pretty.
 610   CollectorPolicy* cp = gch->collector_policy();
 611 
 612   FastScanClosure fsc_with_no_gc_barrier(this, false);
 613   FastScanClosure fsc_with_gc_barrier(this, true);
 614 
 615   KlassScanClosure klass_scan_closure(&fsc_with_no_gc_barrier,
 616                                       gch->rem_set()->klass_rem_set());
 617   CLDToKlassAndOopClosure cld_scan_closure(&klass_scan_closure,
 618                                            &fsc_with_no_gc_barrier,
 619                                            false);
 620 
 621   set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
 622   FastEvacuateFollowersClosure evacuate_followers(gch, _level, this,
 623                                                   &fsc_with_no_gc_barrier,
 624                                                   &fsc_with_gc_barrier);
 625 
 626   assert(gch->no_allocs_since_save_marks(0),
 627          "save marks have not been newly set.");
 628 
 629   {
 630     // DefNew needs to run with n_threads == 0, to make sure the serial
 631     // version of the card table scanning code is used.
 632     // See: CardTableModRefBS::non_clean_card_iterate_possibly_parallel.
 633     StrongRootsScope srs(0);
 634 
 635     gch->gen_process_roots(&srs,
 636                            _level,
 637                            true,  // Process younger gens, if any,
 638                                   // as strong roots.
 639                            GenCollectedHeap::SO_ScavengeCodeCache,
 640                            GenCollectedHeap::StrongAndWeakRoots,
 641                            &fsc_with_no_gc_barrier,
 642                            &fsc_with_gc_barrier,
 643                            &cld_scan_closure);
 644   }
 645 
 646   // "evacuate followers".
 647   evacuate_followers.do_void();
 648 
 649   FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
 650   ReferenceProcessor* rp = ref_processor();
 651   rp->setup_policy(clear_all_soft_refs);
 652   const ReferenceProcessorStats& stats =
 653   rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers,
 654                                     NULL, _gc_timer, gc_tracer.gc_id());
 655   gc_tracer.report_gc_reference_stats(stats);
 656 


 853 }
 854 
 855 #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
 856                                                                 \
 857 void DefNewGeneration::                                         \
 858 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) {   \
 859   cl->set_generation(this);                                     \
 860   eden()->oop_since_save_marks_iterate##nv_suffix(cl);          \
 861   to()->oop_since_save_marks_iterate##nv_suffix(cl);            \
 862   from()->oop_since_save_marks_iterate##nv_suffix(cl);          \
 863   cl->reset_generation();                                       \
 864   save_marks();                                                 \
 865 }
 866 
 867 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN)
 868 
 869 #undef DefNew_SINCE_SAVE_MARKS_DEFN
 870 
 871 void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor,
 872                                          size_t max_alloc_words) {
 873   if (requestor == this || _promotion_failed) return;
 874   assert(requestor->level() > level(), "DefNewGeneration must be youngest");


 875 
 876   /* $$$ Assert this?  "trace" is a "MarkSweep" function so that's not appropriate.
 877   if (to_space->top() > to_space->bottom()) {
 878     trace("to_space not empty when contribute_scratch called");
 879   }
 880   */
 881 
 882   ContiguousSpace* to_space = to();
 883   assert(to_space->end() >= to_space->top(), "pointers out of order");
 884   size_t free_words = pointer_delta(to_space->end(), to_space->top());
 885   if (free_words >= MinFreeScratchWords) {
 886     ScratchBlock* sb = (ScratchBlock*)to_space->top();
 887     sb->num_words = free_words;
 888     sb->next = list;
 889     list = sb;
 890   }
 891 }
 892 
 893 void DefNewGeneration::reset_scratch() {
 894   // If contributing scratch in to_space, mangle all of




  41 #include "gc/shared/strongRootsScope.hpp"
  42 #include "memory/iterator.hpp"
  43 #include "oops/instanceRefKlass.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "runtime/atomic.inline.hpp"
  46 #include "runtime/java.hpp"
  47 #include "runtime/prefetch.inline.hpp"
  48 #include "runtime/thread.inline.hpp"
  49 #include "utilities/copy.hpp"
  50 #include "utilities/globalDefinitions.hpp"
  51 #include "utilities/stack.inline.hpp"
  52 #if INCLUDE_ALL_GCS
  53 #include "gc/cms/parOopClosures.hpp"
  54 #endif
  55 
  56 //
  57 // DefNewGeneration functions.
  58 
  59 // Methods of protected closure types.
  60 
  61 DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* young_gen) : _young_gen(young_gen) {
  62   assert(_young_gen->kind() == Generation::ParNew ||
  63          _young_gen->kind() == Generation::DefNew, "Expected the young generation here");
  64 }
  65 
  66 bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) {
  67   return (HeapWord*)p >= _young_gen->reserved().end() || p->is_forwarded();
  68 }
  69 
  70 DefNewGeneration::KeepAliveClosure::
  71 KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) {
  72   GenRemSet* rs = GenCollectedHeap::heap()->rem_set();
  73   _rs = (CardTableRS*)rs;
  74 }
  75 
  76 void DefNewGeneration::KeepAliveClosure::do_oop(oop* p)       { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
  77 void DefNewGeneration::KeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
  78 
  79 
  80 DefNewGeneration::FastKeepAliveClosure::
  81 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) :
  82   DefNewGeneration::KeepAliveClosure(cl) {
  83   _boundary = g->reserved().end();
  84 }
  85 
  86 void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p)       { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
  87 void DefNewGeneration::FastKeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
  88 
  89 DefNewGeneration::EvacuateFollowersClosure::
  90 EvacuateFollowersClosure(GenCollectedHeap* gch,
  91                          ScanClosure* cur,
  92                          ScanClosure* older) :
  93   _gch(gch), _scan_cur_or_nonheap(cur), _scan_older(older)
  94 {}
  95 
  96 void DefNewGeneration::EvacuateFollowersClosure::do_void() {
  97   do {
  98     _gch->oop_since_save_marks_iterate(Generation::Young, _scan_cur_or_nonheap,
  99                                        _scan_older);
 100   } while (!_gch->no_allocs_since_save_marks(Generation::Young));
 101 }
 102 
 103 DefNewGeneration::FastEvacuateFollowersClosure::
 104 FastEvacuateFollowersClosure(GenCollectedHeap* gch,
 105                              FastScanClosure* cur,
 106                              FastScanClosure* older) :
 107   _gch(gch), _scan_cur_or_nonheap(cur), _scan_older(older)
 108 {
 109   assert(_gch->young_gen()->kind() == Generation::DefNew, "Generation should be DefNew");
 110   _gen = (DefNewGeneration*)_gch->young_gen();
 111 }
 112 
 113 void DefNewGeneration::FastEvacuateFollowersClosure::do_void() {
 114   do {
 115     _gch->oop_since_save_marks_iterate(Generation::Young, _scan_cur_or_nonheap, _scan_older);
 116   } while (!_gch->no_allocs_since_save_marks(Generation::Young));

 117   guarantee(_gen->promo_failure_scan_is_complete(), "Failed to finish scan");
 118 }
 119 
 120 ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) :
 121     OopsInKlassOrGenClosure(g), _g(g), _gc_barrier(gc_barrier)
 122 {

 123   _boundary = _g->reserved().end();
 124 }
 125 
 126 void ScanClosure::do_oop(oop* p)       { ScanClosure::do_oop_work(p); }
 127 void ScanClosure::do_oop(narrowOop* p) { ScanClosure::do_oop_work(p); }
 128 
 129 FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) :
 130     OopsInKlassOrGenClosure(g), _g(g), _gc_barrier(gc_barrier)
 131 {

 132   _boundary = _g->reserved().end();
 133 }
 134 
 135 void FastScanClosure::do_oop(oop* p)       { FastScanClosure::do_oop_work(p); }
 136 void FastScanClosure::do_oop(narrowOop* p) { FastScanClosure::do_oop_work(p); }
 137 
 138 void KlassScanClosure::do_klass(Klass* klass) {
 139 #ifndef PRODUCT
 140   if (TraceScavenge) {
 141     ResourceMark rm;
 142     gclog_or_tty->print_cr("KlassScanClosure::do_klass " PTR_FORMAT ", %s, dirty: %s",
 143                            p2i(klass),
 144                            klass->external_name(),
 145                            klass->has_modified_oops() ? "true" : "false");
 146   }
 147 #endif
 148 
 149   // If the klass has not been dirtied we know that there's
 150   // no references into  the young gen and we can skip it.
 151   if (klass->has_modified_oops()) {
 152     if (_accumulate_modified_oops) {
 153       klass->accumulate_modified_oops();
 154     }
 155 
 156     // Clear this state since we're going to scavenge all the metadata.
 157     klass->clear_modified_oops();
 158 
 159     // Tell the closure which Klass is being scanned so that it can be dirtied
 160     // if oops are left pointing into the young gen.
 161     _scavenge_closure->set_scanned_klass(klass);
 162 
 163     klass->oops_do(_scavenge_closure);
 164 
 165     _scavenge_closure->set_scanned_klass(NULL);
 166   }
 167 }
 168 
 169 ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) :
 170   _g(g)
 171 {

 172   _boundary = _g->reserved().end();
 173 }
 174 
 175 void ScanWeakRefClosure::do_oop(oop* p)       { ScanWeakRefClosure::do_oop_work(p); }
 176 void ScanWeakRefClosure::do_oop(narrowOop* p) { ScanWeakRefClosure::do_oop_work(p); }
 177 
 178 void FilteringClosure::do_oop(oop* p)       { FilteringClosure::do_oop_work(p); }
 179 void FilteringClosure::do_oop(narrowOop* p) { FilteringClosure::do_oop_work(p); }
 180 
 181 KlassScanClosure::KlassScanClosure(OopsInKlassOrGenClosure* scavenge_closure,
 182                                    KlassRemSet* klass_rem_set)
 183     : _scavenge_closure(scavenge_closure),
 184       _accumulate_modified_oops(klass_rem_set->accumulate_modified_oops()) {}
 185 
 186 
 187 DefNewGeneration::DefNewGeneration(ReservedSpace rs,
 188                                    size_t initial_size,

 189                                    const char* policy)
 190   : Generation(rs, initial_size),
 191     _promo_failure_drain_in_progress(false),
 192     _should_allocate_from_space(false)
 193 {
 194   MemRegion cmr((HeapWord*)_virtual_space.low(),
 195                 (HeapWord*)_virtual_space.high());
 196   GenCollectedHeap* gch = GenCollectedHeap::heap();
 197 
 198   gch->barrier_set()->resize_covered_region(cmr);
 199 
 200   _eden_space = new ContiguousSpace();
 201   _from_space = new ContiguousSpace();
 202   _to_space   = new ContiguousSpace();
 203 
 204   if (_eden_space == NULL || _from_space == NULL || _to_space == NULL)
 205     vm_exit_during_initialization("Could not allocate a new gen space");
 206 
 207   // Compute the maximum eden and survivor space sizes. These sizes
 208   // are computed assuming the entire reserved space is committed.
 209   // These values are exported as performance counters.
 210   uintx alignment = gch->collector_policy()->space_alignment();


 354   }
 355 
 356   // Do not attempt an expand-to-the reserve size.  The
 357   // request should properly observe the maximum size of
 358   // the generation so an expand-to-reserve should be
 359   // unnecessary.  Also a second call to expand-to-reserve
 360   // value potentially can cause an undue expansion.
 361   // For example if the first expand fail for unknown reasons,
 362   // but the second succeeds and expands the heap to its maximum
 363   // value.
 364   if (GC_locker::is_active()) {
 365     if (PrintGC && Verbose) {
 366       gclog_or_tty->print_cr("Garbage collection disabled, "
 367         "expanded heap instead");
 368     }
 369   }
 370 
 371   return success;
 372 }
 373 

 374 void DefNewGeneration::compute_new_size() {
 375   // This is called after a GC that includes the old generation, so from-space
 376   // will normally be empty.
 377   // Note that we check both spaces, since if scavenge failed they revert roles.
 378   // If not we bail out (otherwise we would have to relocate the objects).
 379   if (!from()->is_empty() || !to()->is_empty()) {
 380     return;
 381   }
 382 

 383   GenCollectedHeap* gch = GenCollectedHeap::heap();

 384 
 385   size_t old_size = gch->old_gen()->capacity();

 386   size_t new_size_before = _virtual_space.committed_size();
 387   size_t min_new_size = spec()->init_size();
 388   size_t max_new_size = reserved().byte_size();
 389   assert(min_new_size <= new_size_before &&
 390          new_size_before <= max_new_size,
 391          "just checking");
 392   // All space sizes must be multiples of Generation::GenGrain.
 393   size_t alignment = Generation::GenGrain;
 394 
 395   // Compute desired new generation size based on NewRatio and
 396   // NewSizeThreadIncrease
 397   size_t desired_new_size = old_size/NewRatio;
 398   int threads_count = Threads::number_of_non_daemon_threads();
 399   size_t thread_increase_size = threads_count * NewSizeThreadIncrease;
 400   desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment);
 401 
 402   // Adjust new generation size
 403   desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size);
 404   assert(desired_new_size <= max_new_size, "just checking");
 405 


 581   }
 582   assert(to()->is_empty(), "Else not collection_attempt_is_safe");
 583 
 584   init_assuming_no_promotion_failure();
 585 
 586   GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, gc_tracer.gc_id());
 587   // Capture heap used before collection (for printing).
 588   size_t gch_prev_used = gch->used();
 589 
 590   gch->trace_heap_before_gc(&gc_tracer);
 591 
 592   // These can be shared for all code paths
 593   IsAliveClosure is_alive(this);
 594   ScanWeakRefClosure scan_weak_ref(this);
 595 
 596   age_table()->clear();
 597   to()->clear(SpaceDecorator::Mangle);
 598 
 599   gch->rem_set()->prepare_for_younger_refs_iterate(false);
 600 
 601   assert(gch->no_allocs_since_save_marks(Generation::Young),
 602          "save marks have not been newly set.");
 603 
 604   // Not very pretty.
 605   CollectorPolicy* cp = gch->collector_policy();
 606 
 607   FastScanClosure fsc_with_no_gc_barrier(this, false);
 608   FastScanClosure fsc_with_gc_barrier(this, true);
 609 
 610   KlassScanClosure klass_scan_closure(&fsc_with_no_gc_barrier,
 611                                       gch->rem_set()->klass_rem_set());
 612   CLDToKlassAndOopClosure cld_scan_closure(&klass_scan_closure,
 613                                            &fsc_with_no_gc_barrier,
 614                                            false);
 615 
 616   set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
 617   FastEvacuateFollowersClosure evacuate_followers(gch,
 618                                                   &fsc_with_no_gc_barrier,
 619                                                   &fsc_with_gc_barrier);
 620 
 621   assert(gch->no_allocs_since_save_marks(Generation::Young),
 622          "save marks have not been newly set.");
 623 
 624   {
 625     // DefNew needs to run with n_threads == 0, to make sure the serial
 626     // version of the card table scanning code is used.
 627     // See: CardTableModRefBS::non_clean_card_iterate_possibly_parallel.
 628     StrongRootsScope srs(0);
 629 
 630     gch->gen_process_roots(&srs,
 631                            Generation::Young,
 632                            true,  // Process younger gens, if any,
 633                                   // as strong roots.
 634                            GenCollectedHeap::SO_ScavengeCodeCache,
 635                            GenCollectedHeap::StrongAndWeakRoots,
 636                            &fsc_with_no_gc_barrier,
 637                            &fsc_with_gc_barrier,
 638                            &cld_scan_closure);
 639   }
 640 
 641   // "evacuate followers".
 642   evacuate_followers.do_void();
 643 
 644   FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
 645   ReferenceProcessor* rp = ref_processor();
 646   rp->setup_policy(clear_all_soft_refs);
 647   const ReferenceProcessorStats& stats =
 648   rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers,
 649                                     NULL, _gc_timer, gc_tracer.gc_id());
 650   gc_tracer.report_gc_reference_stats(stats);
 651 


 848 }
 849 
 850 #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
 851                                                                 \
 852 void DefNewGeneration::                                         \
 853 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) {   \
 854   cl->set_generation(this);                                     \
 855   eden()->oop_since_save_marks_iterate##nv_suffix(cl);          \
 856   to()->oop_since_save_marks_iterate##nv_suffix(cl);            \
 857   from()->oop_since_save_marks_iterate##nv_suffix(cl);          \
 858   cl->reset_generation();                                       \
 859   save_marks();                                                 \
 860 }
 861 
 862 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN)
 863 
 864 #undef DefNew_SINCE_SAVE_MARKS_DEFN
 865 
 866 void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor,
 867                                          size_t max_alloc_words) {
 868   if (requestor == this || _promotion_failed) {
 869     return;
 870   }
 871   assert(requestor == GenCollectedHeap::heap()->old_gen(), "We should not call our own generation");
 872 
 873   /* $$$ Assert this?  "trace" is a "MarkSweep" function so that's not appropriate.
 874   if (to_space->top() > to_space->bottom()) {
 875     trace("to_space not empty when contribute_scratch called");
 876   }
 877   */
 878 
 879   ContiguousSpace* to_space = to();
 880   assert(to_space->end() >= to_space->top(), "pointers out of order");
 881   size_t free_words = pointer_delta(to_space->end(), to_space->top());
 882   if (free_words >= MinFreeScratchWords) {
 883     ScratchBlock* sb = (ScratchBlock*)to_space->top();
 884     sb->num_words = free_words;
 885     sb->next = list;
 886     list = sb;
 887   }
 888 }
 889 
 890 void DefNewGeneration::reset_scratch() {
 891   // If contributing scratch in to_space, mangle all of


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