jdk8-mips64-public/hotspot: src/share/vm/memory/defNewGeneration.hpp@a7214d79fcf1 (annotated)

src/share/vm/memory/defNewGeneration.hpp@a7214d79fcf1 (annotated)

src/share/vm/memory/defNewGeneration.hpp

Sat, 23 Oct 2010 23:03:49 -0700

author: ysr
date: Sat, 23 Oct 2010 23:03:49 -0700
changeset 2243: a7214d79fcf1
parent 2191: 894b1d7c7e01
child 2314: f95d63e2154a
permissions: -rw-r--r--

6896603: CMS/GCH: collection_attempt_is_safe() ergo should use more recent data
Summary: Deprecated HandlePromotionFailure, removing the ability to turn off that feature, did away with one epoch look-ahead when deciding if a scavenge is likely to fail, relying on current data.
Reviewed-by: jmasa, johnc, poonam

 /*
  * Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 class EdenSpace;
 class ContiguousSpace;
 class ScanClosure;
 // DefNewGeneration is a young generation containing eden, from- and
 // to-space.
 class DefNewGeneration: public Generation {
   friend class VMStructs;
 protected:
   Generation* _next_gen;
   int         _tenuring_threshold;   // Tenuring threshold for next collection.
   ageTable    _age_table;
   // Size of object to pretenure in words; command line provides bytes
   size_t        _pretenure_size_threshold_words;
   ageTable*   age_table() { return &_age_table; }
   // Initialize state to optimistically assume no promotion failure will
   // happen.
   void   init_assuming_no_promotion_failure();
   // True iff a promotion has failed in the current collection.
   bool   _promotion_failed;
   bool   promotion_failed() { return _promotion_failed; }
   // Handling promotion failure.  A young generation collection
   // can fail if a live object cannot be copied out of its
   // location in eden or from-space during the collection.  If
   // a collection fails, the young generation is left in a
   // consistent state such that it can be collected by a
   // full collection.
   //   Before the collection
   //     Objects are in eden or from-space
   //     All roots into the young generation point into eden or from-space.
   //
   //   After a failed collection
   //     Objects may be in eden, from-space, or to-space
   //     An object A in eden or from-space may have a copy B
   //       in to-space.  If B exists, all roots that once pointed
   //       to A must now point to B.
   //     All objects in the young generation are unmarked.
   //     Eden, from-space, and to-space will all be collected by
   //       the full collection.
   void handle_promotion_failure(oop);
   // In the absence of promotion failure, we wouldn't look at "from-space"
   // objects after a young-gen collection.  When promotion fails, however,
   // the subsequent full collection will look at from-space objects:
   // therefore we must remove their forwarding pointers.
   void remove_forwarding_pointers();
   // Preserve the mark of "obj", if necessary, in preparation for its mark
   // word being overwritten with a self-forwarding-pointer.
   void   preserve_mark_if_necessary(oop obj, markOop m);
   // Together, these keep <object with a preserved mark, mark value> pairs.
   // They should always contain the same number of elements.
   Stack<oop>     _objs_with_preserved_marks;
   Stack<markOop> _preserved_marks_of_objs;
   // Promotion failure handling
   OopClosure *_promo_failure_scan_stack_closure;
   void set_promo_failure_scan_stack_closure(OopClosure *scan_stack_closure) {
     _promo_failure_scan_stack_closure = scan_stack_closure;
   }
   Stack<oop> _promo_failure_scan_stack;
   void drain_promo_failure_scan_stack(void);
   bool _promo_failure_drain_in_progress;
   // Performance Counters
   GenerationCounters*  _gen_counters;
   CSpaceCounters*      _eden_counters;
   CSpaceCounters*      _from_counters;
   CSpaceCounters*      _to_counters;
   // sizing information
   size_t               _max_eden_size;
   size_t               _max_survivor_size;
   // Allocation support
   bool _should_allocate_from_space;
   bool should_allocate_from_space() const {
     return _should_allocate_from_space;
   }
   void clear_should_allocate_from_space() {
     _should_allocate_from_space = false;
   }
   void set_should_allocate_from_space() {
     _should_allocate_from_space = true;
   }
  protected:
   // Spaces
   EdenSpace*       _eden_space;
   ContiguousSpace* _from_space;
   ContiguousSpace* _to_space;
   enum SomeProtectedConstants {
     // Generations are GenGrain-aligned and have size that are multiples of
     // GenGrain.
     MinFreeScratchWords = 100
   };
   // Return the size of a survivor space if this generation were of size
   // gen_size.
   size_t compute_survivor_size(size_t gen_size, size_t alignment) const {
     size_t n = gen_size / (SurvivorRatio + 2);
     return n > alignment ? align_size_down(n, alignment) : alignment;
   }
  public:  // was "protected" but caused compile error on win32
   class IsAliveClosure: public BoolObjectClosure {
     Generation* _g;
   public:
     IsAliveClosure(Generation* g);
     void do_object(oop p);
     bool do_object_b(oop p);
   };
   class KeepAliveClosure: public OopClosure {
   protected:
     ScanWeakRefClosure* _cl;
     CardTableRS* _rs;
     template <class T> void do_oop_work(T* p);
   public:
     KeepAliveClosure(ScanWeakRefClosure* cl);
     virtual void do_oop(oop* p);
     virtual void do_oop(narrowOop* p);
   };
   class FastKeepAliveClosure: public KeepAliveClosure {
   protected:
     HeapWord* _boundary;
     template <class T> void do_oop_work(T* p);
   public:
     FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl);
     virtual void do_oop(oop* p);
     virtual void do_oop(narrowOop* p);
   };
   class EvacuateFollowersClosure: public VoidClosure {
     GenCollectedHeap* _gch;
     int _level;
     ScanClosure* _scan_cur_or_nonheap;
     ScanClosure* _scan_older;
   public:
     EvacuateFollowersClosure(GenCollectedHeap* gch, int level,
                              ScanClosure* cur, ScanClosure* older);
     void do_void();
   };
   class FastEvacuateFollowersClosure: public VoidClosure {
     GenCollectedHeap* _gch;
     int _level;
     DefNewGeneration* _gen;
     FastScanClosure* _scan_cur_or_nonheap;
     FastScanClosure* _scan_older;
   public:
     FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level,
                                  DefNewGeneration* gen,
                                  FastScanClosure* cur,
                                  FastScanClosure* older);
     void do_void();
   };
  public:
   DefNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
                    const char* policy="Copy");
   virtual Generation::Name kind() { return Generation::DefNew; }
   // Accessing spaces
   EdenSpace*       eden() const           { return _eden_space; }
   ContiguousSpace* from() const           { return _from_space;  }
   ContiguousSpace* to()   const           { return _to_space;    }
   virtual CompactibleSpace* first_compaction_space() const;
   // Space enquiries
   size_t capacity() const;
   size_t used() const;
   size_t free() const;
   size_t max_capacity() const;
   size_t capacity_before_gc() const;
   size_t unsafe_max_alloc_nogc() const;
   size_t contiguous_available() const;
   size_t max_eden_size() const              { return _max_eden_size; }
   size_t max_survivor_size() const          { return _max_survivor_size; }
   bool supports_inline_contig_alloc() const { return true; }
   HeapWord** top_addr() const;
   HeapWord** end_addr() const;
   // Thread-local allocation buffers
   bool supports_tlab_allocation() const { return true; }
   size_t tlab_capacity() const;
   size_t unsafe_max_tlab_alloc() const;
   // Grow the generation by the specified number of bytes.
   // The size of bytes is assumed to be properly aligned.
   // Return true if the expansion was successful.
   bool expand(size_t bytes);
   // DefNewGeneration cannot currently expand except at
   // a GC.
   virtual bool is_maximal_no_gc() const { return true; }
   // Iteration
   void object_iterate(ObjectClosure* blk);
   void object_iterate_since_last_GC(ObjectClosure* cl);
   void younger_refs_iterate(OopsInGenClosure* cl);
   void space_iterate(SpaceClosure* blk, bool usedOnly = false);
   // Allocation support
   virtual bool should_allocate(size_t word_size, bool is_tlab) {
     assert(UseTLAB || !is_tlab, "Should not allocate tlab");
     size_t overflow_limit    = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
     const bool non_zero      = word_size > 0;
     const bool overflows     = word_size >= overflow_limit;
     const bool check_too_big = _pretenure_size_threshold_words > 0;
     const bool not_too_big   = word_size < _pretenure_size_threshold_words;
     const bool size_ok       = is_tlab || !check_too_big || not_too_big;
     bool result = !overflows &&
                   non_zero   &&
                   size_ok;
     return result;
   }
   HeapWord* allocate(size_t word_size, bool is_tlab);
   HeapWord* allocate_from_space(size_t word_size);
   HeapWord* par_allocate(size_t word_size, bool is_tlab);
   // Prologue & Epilogue
   virtual void gc_prologue(bool full);
   virtual void gc_epilogue(bool full);
   // Save the tops for eden, from, and to
   virtual void record_spaces_top();
   // Doesn't require additional work during GC prologue and epilogue
   virtual bool performs_in_place_marking() const { return false; }
   // Accessing marks
   void save_marks();
   void reset_saved_marks();
   bool no_allocs_since_save_marks();
   // Need to declare the full complement of closures, whether we'll
   // override them or not, or get message from the compiler:
   //   oop_since_save_marks_iterate_nv hides virtual function...
 #define DefNew_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
   void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
   ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DECL)
 #undef DefNew_SINCE_SAVE_MARKS_DECL
   // For non-youngest collection, the DefNewGeneration can contribute
   // "to-space".
   virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
                           size_t max_alloc_words);
   // Reset for contribution of "to-space".
   virtual void reset_scratch();
   // GC support
   virtual void compute_new_size();
   // Returns true if the collection is likely to be safely
   // completed. Even if this method returns true, a collection
   // may not be guaranteed to succeed, and the system should be
   // able to safely unwind and recover from that failure, albeit
   // at some additional cost. Override superclass's implementation.
   virtual bool collection_attempt_is_safe();
   virtual void collect(bool   full,
                        bool   clear_all_soft_refs,
                        size_t size,
                        bool   is_tlab);
   HeapWord* expand_and_allocate(size_t size,
                                 bool is_tlab,
                                 bool parallel = false);
   oop copy_to_survivor_space(oop old);
   int tenuring_threshold() { return _tenuring_threshold; }
   // Performance Counter support
   void update_counters();
   // Printing
   virtual const char* name() const;
   virtual const char* short_name() const { return "DefNew"; }
   bool must_be_youngest() const { return true; }
   bool must_be_oldest() const { return false; }
   // PrintHeapAtGC support.
   void print_on(outputStream* st) const;
   void verify(bool allow_dirty);
   bool promo_failure_scan_is_complete() const {
     return _promo_failure_scan_stack.is_empty();
   }
  protected:
   // If clear_space is true, clear the survivor spaces.  Eden is
   // cleared if the minimum size of eden is 0.  If mangle_space
   // is true, also mangle the space in debug mode.
   void compute_space_boundaries(uintx minimum_eden_size,
                                 bool clear_space,
                                 bool mangle_space);
   // Scavenge support
   void swap_spaces();
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/defNewGeneration.hpp@a7214d79fcf1 (annotated)

src/share/vm/memory/defNewGeneration.hpp