src/share/vm/classfile/symbolTable.hpp

rev 4551 : 8015237: Parallelize string table scanning during strong root processing
Summary: Parallelize the scanning of the intern string table by having each GC worker claim a given number of buckets. Changes were also reviewed by Per Liden <per.liden@oracle.com>.
Reviewed-by: tschatzl, stefank, twisti

*** 1,7 ****
  /*
!  * Copyright (c) 1997, 2012, 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.
--- 1,7 ----
  /*
!  * Copyright (c) 1997, 2013, 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.
*** 243,258 ****
--- 243,265 ----
    static StringTable* _the_table;
  
    // Set if one bucket is out of balance due to hash algorithm deficiency
    static bool _needs_rehashing;
  
+   // Claimed high water mark for parallel chunked scanning
+   static volatile int _parallel_claimed_idx;
+ 
    static oop intern(Handle string_or_null, jchar* chars, int length, TRAPS);
    oop basic_add(int index, Handle string_or_null, jchar* name, int len,
                  unsigned int hashValue, TRAPS);
  
    oop lookup(int index, jchar* chars, int length, unsigned int hashValue);
  
+   // Apply the give oop closure to the entries to the buckets
+   // in the range [start_idx, end_idx).
+   static void buckets_do(OopClosure* f, int start_idx, int end_idx);
+ 
    StringTable() : Hashtable<oop, mtSymbol>((int)StringTableSize,
                                sizeof (HashtableEntry<oop, mtSymbol>)) {}
  
    StringTable(HashtableBucket<mtSymbol>* t, int number_of_entries)
      : Hashtable<oop, mtSymbol>((int)StringTableSize, sizeof (HashtableEntry<oop, mtSymbol>), t,
*** 276,288 ****
  
    // GC support
    //   Delete pointers to otherwise-unreachable objects.
    static void unlink(BoolObjectClosure* cl);
  
!   // Invoke "f->do_oop" on the locations of all oops in the table.
    static void oops_do(OopClosure* f);
  
    // Hashing algorithm, used as the hash value used by the
    //     StringTable for bucket selection and comparison (stored in the
    //     HashtableEntry structures).  This is used in the String.intern() method.
    static unsigned int hash_string(const jchar* s, int len);
  
--- 283,298 ----
  
    // GC support
    //   Delete pointers to otherwise-unreachable objects.
    static void unlink(BoolObjectClosure* cl);
  
!   // Serially invoke "f->do_oop" on the locations of all oops in the table.
    static void oops_do(OopClosure* f);
  
+   // Possibly parallel version of the above
+   static void possibly_parallel_oops_do(OopClosure* f);
+ 
    // Hashing algorithm, used as the hash value used by the
    //     StringTable for bucket selection and comparison (stored in the
    //     HashtableEntry structures).  This is used in the String.intern() method.
    static unsigned int hash_string(const jchar* s, int len);
  
*** 313,319 ****
--- 323,332 ----
    }
  
    // Rehash the symbol table if it gets out of balance
    static void rehash_table();
    static bool needs_rehashing() { return _needs_rehashing; }
+ 
+   // Parallel chunked scanning
+   static void clear_parallel_claimed_index() { _parallel_claimed_idx = 0; }
  };
  #endif // SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP