changeset 3247:fc9d8850ab8b

7150058: Allocate symbols from null boot loader to an arena for NMT Summary: Move symbol allocation to an arena so NMT doesn't have to track them at startup. Reviewed-by: never, kamg, zgu
author coleenp
date Fri, 23 Mar 2012 11:16:05 -0400
parents 51612f0c0a79
children a4ee440d71cc
files src/share/vm/classfile/classFileParser.cpp src/share/vm/classfile/classFileParser.hpp src/share/vm/classfile/symbolTable.cpp src/share/vm/classfile/symbolTable.hpp src/share/vm/classfile/vmSymbols.cpp src/share/vm/memory/dump.cpp src/share/vm/oops/objArrayKlassKlass.cpp src/share/vm/oops/symbol.cpp src/share/vm/oops/symbol.hpp src/share/vm/oops/typeArrayKlass.cpp src/share/vm/runtime/globals.hpp
diffstat 11 files changed, 162 insertions(+), 126 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/classfile/classFileParser.cpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/classfile/classFileParser.cpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -81,7 +81,7 @@
 #define JAVA_7_VERSION                    51
 
 
-void ClassFileParser::parse_constant_pool_entries(constantPoolHandle cp, int length, TRAPS) {
+void ClassFileParser::parse_constant_pool_entries(Handle class_loader, constantPoolHandle cp, int length, TRAPS) {
   // Use a local copy of ClassFileStream. It helps the C++ compiler to optimize
   // this function (_current can be allocated in a register, with scalar
   // replacement of aggregates). The _current pointer is copied back to
@@ -272,7 +272,7 @@
             indices[names_count] = index;
             hashValues[names_count++] = hash;
             if (names_count == SymbolTable::symbol_alloc_batch_size) {
-              SymbolTable::new_symbols(cp, names_count, names, lengths, indices, hashValues, CHECK);
+              SymbolTable::new_symbols(class_loader, cp, names_count, names, lengths, indices, hashValues, CHECK);
               names_count = 0;
             }
           } else {
@@ -289,7 +289,7 @@
 
   // Allocate the remaining symbols
   if (names_count > 0) {
-    SymbolTable::new_symbols(cp, names_count, names, lengths, indices, hashValues, CHECK);
+    SymbolTable::new_symbols(class_loader, cp, names_count, names, lengths, indices, hashValues, CHECK);
   }
 
   // Copy _current pointer of local copy back to stream().
@@ -318,7 +318,7 @@
 
 bool inline valid_cp_range(int index, int length) { return (index > 0 && index < length); }
 
-constantPoolHandle ClassFileParser::parse_constant_pool(TRAPS) {
+constantPoolHandle ClassFileParser::parse_constant_pool(Handle class_loader, TRAPS) {
   ClassFileStream* cfs = stream();
   constantPoolHandle nullHandle;
 
@@ -337,7 +337,7 @@
   ConstantPoolCleaner cp_in_error(cp); // set constant pool to be cleaned up.
 
   // parsing constant pool entries
-  parse_constant_pool_entries(cp, length, CHECK_(nullHandle));
+  parse_constant_pool_entries(class_loader, cp, length, CHECK_(nullHandle));
 
   int index = 1;  // declared outside of loops for portability
 
@@ -2758,7 +2758,7 @@
   _relax_verify = Verifier::relax_verify_for(class_loader());
 
   // Constant pool
-  constantPoolHandle cp = parse_constant_pool(CHECK_(nullHandle));
+  constantPoolHandle cp = parse_constant_pool(class_loader, CHECK_(nullHandle));
   ConstantPoolCleaner error_handler(cp); // set constant pool to be cleaned up.
 
   int cp_size = cp->length();
--- a/src/share/vm/classfile/classFileParser.hpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/classfile/classFileParser.hpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -68,9 +68,10 @@
   void set_stream(ClassFileStream* st)             { _stream = st; }
 
   // Constant pool parsing
-  void parse_constant_pool_entries(constantPoolHandle cp, int length, TRAPS);
+  void parse_constant_pool_entries(Handle class_loader,
+                                   constantPoolHandle cp, int length, TRAPS);
 
-  constantPoolHandle parse_constant_pool(TRAPS);
+  constantPoolHandle parse_constant_pool(Handle class_loader, TRAPS);
 
   // Interface parsing
   objArrayHandle parse_interfaces(constantPoolHandle cp,
--- a/src/share/vm/classfile/symbolTable.cpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/classfile/symbolTable.cpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -27,6 +27,7 @@
 #include "classfile/symbolTable.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "gc_interface/collectedHeap.inline.hpp"
+#include "memory/allocation.inline.hpp"
 #include "memory/filemap.hpp"
 #include "memory/gcLocker.inline.hpp"
 #include "oops/oop.inline.hpp"
@@ -37,34 +38,35 @@
 // --------------------------------------------------------------------------
 
 SymbolTable* SymbolTable::_the_table = NULL;
+// Static arena for symbols that are not deallocated
+Arena* SymbolTable::_arena = NULL;
 
-Symbol* SymbolTable::allocate_symbol(const u1* name, int len, TRAPS) {
+Symbol* SymbolTable::allocate_symbol(const u1* name, int len, bool c_heap, TRAPS) {
   // Don't allow symbols to be created which cannot fit in a Symbol*.
   if (len > Symbol::max_length()) {
     THROW_MSG_0(vmSymbols::java_lang_InternalError(),
                 "name is too long to represent");
   }
-  Symbol* sym = new (len) Symbol(name, len);
+  Symbol* sym;
+  // Allocate symbols in the C heap when dumping shared spaces in case there
+  // are temporary symbols we can remove.
+  if (c_heap || DumpSharedSpaces) {
+    // refcount starts as 1
+    sym = new (len, THREAD) Symbol(name, len, 1);
+  } else {
+    sym = new (len, arena(), THREAD) Symbol(name, len, -1);
+  }
   assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted");
   return sym;
 }
 
-bool SymbolTable::allocate_symbols(int names_count, const u1** names,
-                                   int* lengths, Symbol** syms, TRAPS) {
-  for (int i = 0; i< names_count; i++) {
-    if (lengths[i] > Symbol::max_length()) {
-      THROW_MSG_0(vmSymbols::java_lang_InternalError(),
-                  "name is too long to represent");
-    }
+void SymbolTable::initialize_symbols(int arena_alloc_size) {
+  // Initialize the arena for global symbols, size passed in depends on CDS.
+  if (arena_alloc_size == 0) {
+    _arena = new Arena();
+  } else {
+    _arena = new Arena(arena_alloc_size);
   }
-
-  for (int i = 0; i< names_count; i++) {
-    int len = lengths[i];
-    syms[i] = new (len) Symbol(names[i], len);
-    assert(syms[i] != NULL, "new should call vm_exit_out_of_memory if "
-                            "C_HEAP is exhausted");
-  }
-  return true;
 }
 
 // Call function for all symbols in the symbol table.
@@ -83,8 +85,7 @@
 int SymbolTable::symbols_counted = 0;
 
 // Remove unreferenced symbols from the symbol table
-// This is done late during GC.  This doesn't use the hash table unlink because
-// it assumes that the literals are oops.
+// This is done late during GC.
 void SymbolTable::unlink() {
   int removed = 0;
   int total = 0;
@@ -156,7 +157,7 @@
   if (s != NULL) return s;
 
   // Otherwise, add to symbol to table
-  return the_table()->basic_add(index, (u1*)name, len, hashValue, CHECK_NULL);
+  return the_table()->basic_add(index, (u1*)name, len, hashValue, true, CHECK_NULL);
 }
 
 Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) {
@@ -192,7 +193,7 @@
   // We can't include the code in No_Safepoint_Verifier because of the
   // ResourceMark.
 
-  return the_table()->basic_add(index, (u1*)buffer, len, hashValue, CHECK_NULL);
+  return the_table()->basic_add(index, (u1*)buffer, len, hashValue, true, CHECK_NULL);
 }
 
 Symbol* SymbolTable::lookup_only(const char* name, int len,
@@ -256,71 +257,81 @@
   }
 }
 
-void SymbolTable::add(constantPoolHandle cp, int names_count,
+void SymbolTable::add(Handle class_loader, constantPoolHandle cp,
+                      int names_count,
                       const char** names, int* lengths, int* cp_indices,
                       unsigned int* hashValues, TRAPS) {
   SymbolTable* table = the_table();
-  bool added = table->basic_add(cp, names_count, names, lengths,
+  bool added = table->basic_add(class_loader, cp, names_count, names, lengths,
                                 cp_indices, hashValues, CHECK);
   if (!added) {
     // do it the hard way
     for (int i=0; i<names_count; i++) {
       int index = table->hash_to_index(hashValues[i]);
-      Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i],
-                                       hashValues[i], CHECK);
+      bool c_heap = class_loader() != NULL;
+      Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], c_heap, CHECK);
       cp->symbol_at_put(cp_indices[i], sym);
     }
   }
 }
 
+Symbol* SymbolTable::new_permanent_symbol(const char* name, TRAPS) {
+  unsigned int hash;
+  Symbol* result = SymbolTable::lookup_only((char*)name, (int)strlen(name), hash);
+  if (result != NULL) {
+    return result;
+  }
+  SymbolTable* table = the_table();
+  int index = table->hash_to_index(hash);
+  return table->basic_add(index, (u1*)name, (int)strlen(name), hash, false, THREAD);
+}
+
 Symbol* SymbolTable::basic_add(int index, u1 *name, int len,
-                                 unsigned int hashValue, TRAPS) {
+                               unsigned int hashValue, bool c_heap, TRAPS) {
   assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
          "proposed name of symbol must be stable");
 
-  // We assume that lookup() has been called already, that it failed,
-  // and symbol was not found.  We create the symbol here.
-  Symbol* sym = allocate_symbol(name, len, CHECK_NULL);
-
-  // Allocation must be done before grabbing the SymbolTable_lock lock
+  // Grab SymbolTable_lock first.
   MutexLocker ml(SymbolTable_lock, THREAD);
 
-  assert(sym->equals((char*)name, len), "symbol must be properly initialized");
-
   // Since look-up was done lock-free, we need to check if another
   // thread beat us in the race to insert the symbol.
-
   Symbol* test = lookup(index, (char*)name, len, hashValue);
   if (test != NULL) {
-    // A race occurred and another thread introduced the symbol, this one
-    // will be dropped and collected.
-    delete sym;
+    // A race occurred and another thread introduced the symbol.
     assert(test->refcount() != 0, "lookup should have incremented the count");
     return test;
   }
 
+  // Create a new symbol.
+  Symbol* sym = allocate_symbol(name, len, c_heap, CHECK_NULL);
+  assert(sym->equals((char*)name, len), "symbol must be properly initialized");
+
   HashtableEntry<Symbol*>* entry = new_entry(hashValue, sym);
-  sym->increment_refcount();
   add_entry(index, entry);
   return sym;
 }
 
-bool SymbolTable::basic_add(constantPoolHandle cp, int names_count,
+// This version of basic_add adds symbols in batch from the constant pool
+// parsing.
+bool SymbolTable::basic_add(Handle class_loader, constantPoolHandle cp,
+                            int names_count,
                             const char** names, int* lengths,
                             int* cp_indices, unsigned int* hashValues,
                             TRAPS) {
-  Symbol* syms[symbol_alloc_batch_size];
-  bool allocated = allocate_symbols(names_count, (const u1**)names, lengths,
-                                    syms, CHECK_false);
-  if (!allocated) {
-    return false;
+
+  // Check symbol names are not too long.  If any are too long, don't add any.
+  for (int i = 0; i< names_count; i++) {
+    if (lengths[i] > Symbol::max_length()) {
+      THROW_MSG_0(vmSymbols::java_lang_InternalError(),
+                  "name is too long to represent");
+    }
   }
 
-  // Allocation must be done before grabbing the SymbolTable_lock lock
+  // Hold SymbolTable_lock through the symbol creation
   MutexLocker ml(SymbolTable_lock, THREAD);
 
   for (int i=0; i<names_count; i++) {
-    assert(syms[i]->equals(names[i], lengths[i]), "symbol must be properly initialized");
     // Since look-up was done lock-free, we need to check if another
     // thread beat us in the race to insert the symbol.
     int index = hash_to_index(hashValues[i]);
@@ -330,16 +341,17 @@
       // will be dropped and collected. Use test instead.
       cp->symbol_at_put(cp_indices[i], test);
       assert(test->refcount() != 0, "lookup should have incremented the count");
-      delete syms[i];
     } else {
-      Symbol* sym = syms[i];
+      // Create a new symbol.  The null class loader is never unloaded so these
+      // are allocated specially in a permanent arena.
+      bool c_heap = class_loader() != NULL;
+      Symbol* sym = allocate_symbol((const u1*)names[i], lengths[i], c_heap, CHECK_(false));
+      assert(sym->equals(names[i], lengths[i]), "symbol must be properly initialized");  // why wouldn't it be???
       HashtableEntry<Symbol*>* entry = new_entry(hashValues[i], sym);
-      sym->increment_refcount();  // increment refcount in external hashtable
       add_entry(index, entry);
       cp->symbol_at_put(cp_indices[i], sym);
     }
   }
-
   return true;
 }
 
@@ -406,6 +418,8 @@
           ((float)symbols_removed/(float)symbols_counted)* 100);
   }
   tty->print_cr("Reference counts         %5d", Symbol::_total_count);
+  tty->print_cr("Symbol arena size        %5d used %5d",
+                 arena()->size_in_bytes(), arena()->used());
   tty->print_cr("Histogram of symbol length:");
   tty->print_cr("%8s %5d", "Total  ", total);
   tty->print_cr("%8s %5d", "Maximum", max_symbols);
--- a/src/share/vm/classfile/symbolTable.hpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/classfile/symbolTable.hpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -82,24 +82,24 @@
   static int symbols_removed;
   static int symbols_counted;
 
-  Symbol* allocate_symbol(const u1* name, int len, TRAPS);   // Assumes no characters larger than 0x7F
-  bool allocate_symbols(int names_count, const u1** names, int* lengths, Symbol** syms, TRAPS);
+  Symbol* allocate_symbol(const u1* name, int len, bool c_heap, TRAPS); // Assumes no characters larger than 0x7F
 
   // Adding elements
-  Symbol* basic_add(int index, u1* name, int len,
-                      unsigned int hashValue, TRAPS);
-  bool basic_add(constantPoolHandle cp, int names_count,
+  Symbol* basic_add(int index, u1* name, int len, unsigned int hashValue,
+                    bool c_heap, TRAPS);
+
+  bool basic_add(Handle class_loader, constantPoolHandle cp, int names_count,
                  const char** names, int* lengths, int* cp_indices,
                  unsigned int* hashValues, TRAPS);
 
-  static void new_symbols(constantPoolHandle cp, int names_count,
+  static void new_symbols(Handle class_loader, constantPoolHandle cp,
+                          int names_count,
                           const char** name, int* lengths,
                           int* cp_indices, unsigned int* hashValues,
                           TRAPS) {
-    add(cp, names_count, name, lengths, cp_indices, hashValues, THREAD);
+    add(class_loader, cp, names_count, name, lengths, cp_indices, hashValues, THREAD);
   }
 
-
   // Table size
   enum {
     symbol_table_size = 20011
@@ -114,10 +114,16 @@
     : Hashtable<Symbol*>(symbol_table_size, sizeof (HashtableEntry<Symbol*>), t,
                 number_of_entries) {}
 
+  // Arena for permanent symbols (null class loader) that are never unloaded
+  static Arena*  _arena;
+  static Arena* arena() { return _arena; }  // called for statistics
 
+  static void initialize_symbols(int arena_alloc_size = 0);
 public:
   enum {
-    symbol_alloc_batch_size = 8
+    symbol_alloc_batch_size = 8,
+    // Pick initial size based on java -version size measurements
+    symbol_alloc_arena_size = 360*K
   };
 
   // The symbol table
@@ -126,6 +132,7 @@
   static void create_table() {
     assert(_the_table == NULL, "One symbol table allowed.");
     _the_table = new SymbolTable();
+    initialize_symbols(symbol_alloc_arena_size);
   }
 
   static void create_table(HashtableBucket* t, int length,
@@ -134,6 +141,9 @@
     assert(length == symbol_table_size * sizeof(HashtableBucket),
            "bad shared symbol size.");
     _the_table = new SymbolTable(t, number_of_entries);
+    // if CDS give symbol table a default arena size since most symbols
+    // are already allocated in the shared misc section.
+    initialize_symbols();
   }
 
   static Symbol* lookup(const char* name, int len, TRAPS);
@@ -151,7 +161,7 @@
   static Symbol* lookup_unicode(const jchar* name, int len, TRAPS);
   static Symbol* lookup_only_unicode(const jchar* name, int len, unsigned int& hash);
 
-  static void add(constantPoolHandle cp, int names_count,
+  static void add(Handle class_loader, constantPoolHandle cp, int names_count,
                   const char** names, int* lengths, int* cp_indices,
                   unsigned int* hashValues, TRAPS);
 
@@ -174,6 +184,9 @@
     return lookup(sym, begin, end, THREAD);
   }
 
+  // Create a symbol in the arena for symbols that are not deleted
+  static Symbol* new_permanent_symbol(const char* name, TRAPS);
+
   // Symbol lookup
   static Symbol* lookup(int index, const char* name, int len, TRAPS);
 
--- a/src/share/vm/classfile/vmSymbols.cpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/classfile/vmSymbols.cpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -79,7 +79,7 @@
   if (!UseSharedSpaces) {
     const char* string = &vm_symbol_bodies[0];
     for (int index = (int)FIRST_SID; index < (int)SID_LIMIT; index++) {
-      Symbol* sym = SymbolTable::new_symbol(string, CHECK);
+      Symbol* sym = SymbolTable::new_permanent_symbol(string, CHECK);
       _symbols[index] = sym;
       string += strlen(string); // skip string body
       string += 1;              // skip trailing null
@@ -128,7 +128,7 @@
     // Spot-check correspondence between strings, symbols, and enums:
     assert(_symbols[NO_SID] == NULL, "must be");
     const char* str = "java/lang/Object";
-    TempNewSymbol jlo = SymbolTable::new_symbol(str, CHECK);
+    TempNewSymbol jlo = SymbolTable::new_permanent_symbol(str, CHECK);
     assert(strncmp(str, (char*)jlo->base(), jlo->utf8_length()) == 0, "");
     assert(jlo == java_lang_Object(), "");
     SID sid = VM_SYMBOL_ENUM_NAME(java_lang_Object);
@@ -147,7 +147,7 @@
     // The string "format" happens (at the moment) not to be a vmSymbol,
     // though it is a method name in java.lang.String.
     str = "format";
-    TempNewSymbol fmt = SymbolTable::new_symbol(str, CHECK);
+    TempNewSymbol fmt = SymbolTable::new_permanent_symbol(str, CHECK);
     sid = find_sid(fmt);
     assert(sid == NO_SID, "symbol index works (negative test)");
   }
--- a/src/share/vm/memory/dump.cpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/memory/dump.cpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 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
@@ -1490,12 +1490,11 @@
 
     // sun.io.Converters
     static const char obj_array_sig[] = "[[Ljava/lang/Object;";
-    SymbolTable::lookup(obj_array_sig, (int)strlen(obj_array_sig), THREAD);
+    (void)SymbolTable::new_permanent_symbol(obj_array_sig, THREAD);
 
     // java.util.HashMap
     static const char map_entry_array_sig[] = "[Ljava/util/Map$Entry;";
-    SymbolTable::lookup(map_entry_array_sig, (int)strlen(map_entry_array_sig),
-                        THREAD);
+    (void)SymbolTable::new_permanent_symbol(map_entry_array_sig, THREAD);
 
     tty->print("Loading classes to share ... ");
     while ((fgets(class_name, sizeof class_name, file)) != NULL) {
@@ -1514,7 +1513,7 @@
       computed_jsum = jsum(computed_jsum, class_name, (const int)name_len - 1);
 
       // Got a class name - load it.
-      TempNewSymbol class_name_symbol = SymbolTable::new_symbol(class_name, THREAD);
+      Symbol* class_name_symbol = SymbolTable::new_permanent_symbol(class_name, THREAD);
       guarantee(!HAS_PENDING_EXCEPTION, "Exception creating a symbol.");
       klassOop klass = SystemDictionary::resolve_or_null(class_name_symbol,
                                                          THREAD);
--- a/src/share/vm/oops/objArrayKlassKlass.cpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/oops/objArrayKlassKlass.cpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -137,7 +137,7 @@
       new_str[idx++] = ';';
     }
     new_str[idx++] = '\0';
-    name = SymbolTable::new_symbol(new_str, CHECK_0);
+    name = SymbolTable::new_permanent_symbol(new_str, CHECK_0);
     if (element_klass->oop_is_instance()) {
       instanceKlass* ik = instanceKlass::cast(element_klass());
       ik->set_array_name(name);
--- a/src/share/vm/oops/symbol.cpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/oops/symbol.cpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -29,15 +29,25 @@
 #include "runtime/os.hpp"
 #include "memory/allocation.inline.hpp"
 
-Symbol::Symbol(const u1* name, int length) : _refcount(0), _length(length) {
+Symbol::Symbol(const u1* name, int length, int refcount) : _refcount(refcount), _length(length) {
   _identity_hash = os::random();
   for (int i = 0; i < _length; i++) {
     byte_at_put(i, name[i]);
   }
 }
 
-void* Symbol::operator new(size_t size, int len) {
-  return (void *) AllocateHeap(object_size(len) * HeapWordSize, "symbol");
+void* Symbol::operator new(size_t sz, int len, TRAPS) {
+  int alloc_size = object_size(len)*HeapWordSize;
+  address res = (address) AllocateHeap(alloc_size, "symbol");
+  DEBUG_ONLY(set_allocation_type(res, ResourceObj::C_HEAP);)
+  return res;
+}
+
+void* Symbol::operator new(size_t sz, int len, Arena* arena, TRAPS) {
+  int alloc_size = object_size(len)*HeapWordSize;
+  address res = (address)arena->Amalloc(alloc_size);
+  DEBUG_ONLY(set_allocation_type(res, ResourceObj::ARENA);)
+  return res;
 }
 
 // ------------------------------------------------------------------
@@ -206,26 +216,5 @@
   }
 }
 
-void Symbol::increment_refcount() {
-  // Only increment the refcount if positive.  If negative either
-  // overflow has occurred or it is a permanent symbol in a read only
-  // shared archive.
-  if (_refcount >= 0) {
-    Atomic::inc(&_refcount);
-    NOT_PRODUCT(Atomic::inc(&_total_count);)
-  }
-}
-
-void Symbol::decrement_refcount() {
-  if (_refcount >= 0) {
-    Atomic::dec(&_refcount);
-#ifdef ASSERT
-    if (_refcount < 0) {
-      print();
-      assert(false, "reference count underflow for symbol");
-    }
-#endif
-  }
-}
-
+// SymbolTable prints this in its statistics
 NOT_PRODUCT(int Symbol::_total_count = 0;)
--- a/src/share/vm/oops/symbol.hpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/oops/symbol.hpp	Fri Mar 23 11:16:05 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -27,6 +27,7 @@
 
 #include "utilities/utf8.hpp"
 #include "memory/allocation.hpp"
+#include "runtime/atomic.hpp"
 
 // A Symbol is a canonicalized string.
 // All Symbols reside in global SymbolTable and are reference counted.
@@ -95,7 +96,7 @@
 // TempNewSymbol (passed in as a parameter) so the reference count on its symbol
 // will be decremented when it goes out of scope.
 
-class Symbol : public CHeapObj {
+class Symbol : public ResourceObj {
   friend class VMStructs;
   friend class SymbolTable;
   friend class MoveSymbols;
@@ -111,7 +112,7 @@
   };
 
   static int object_size(int length) {
-    size_t size = heap_word_size(sizeof(Symbol) + length);
+    size_t size = heap_word_size(sizeof(Symbol) + (length > 0 ? length - 1 : 0));
     return align_object_size(size);
   }
 
@@ -120,28 +121,25 @@
     _body[index] = value;
   }
 
-  Symbol(const u1* name, int length);
-  void* operator new(size_t size, int len);
+  Symbol(const u1* name, int length, int refcount);
+  void* operator new(size_t size, int len, TRAPS);
+  void* operator new(size_t size, int len, Arena* arena, TRAPS);
 
  public:
   // Low-level access (used with care, since not GC-safe)
   const jbyte* base() const { return &_body[0]; }
 
-  int object_size() { return object_size(utf8_length()); }
+  int object_size()         { return object_size(utf8_length()); }
 
   // Returns the largest size symbol we can safely hold.
-  static int max_length() {
-    return max_symbol_length;
-  }
+  static int max_length()   { return max_symbol_length; }
 
-  int identity_hash() {
-    return _identity_hash;
-  }
+  int identity_hash()       { return _identity_hash; }
 
   // Reference counting.  See comments above this class for when to use.
-  int refcount() const { return _refcount; }
-  void increment_refcount();
-  void decrement_refcount();
+  int refcount() const      { return _refcount; }
+  inline void increment_refcount();
+  inline void decrement_refcount();
 
   int byte_at(int index) const {
     assert(index >=0 && index < _length, "symbol index overflow");
@@ -220,4 +218,26 @@
  return (((uintptr_t)this < (uintptr_t)other) ? -1
    : ((uintptr_t)this == (uintptr_t) other) ? 0 : 1);
 }
+
+inline void Symbol::increment_refcount() {
+  // Only increment the refcount if positive.  If negative either
+  // overflow has occurred or it is a permanent symbol in a read only
+  // shared archive.
+  if (_refcount >= 0) {
+    Atomic::inc(&_refcount);
+    NOT_PRODUCT(Atomic::inc(&_total_count);)
+  }
+}
+
+inline void Symbol::decrement_refcount() {
+  if (_refcount >= 0) {
+    Atomic::dec(&_refcount);
+#ifdef ASSERT
+    if (_refcount < 0) {
+      print();
+      assert(false, "reference count underflow for symbol");
+    }
+#endif
+  }
+}
 #endif // SHARE_VM_OOPS_SYMBOL_HPP
--- a/src/share/vm/oops/typeArrayKlass.cpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/oops/typeArrayKlass.cpp	Fri Mar 23 11:16:05 2012 -0400
@@ -55,7 +55,7 @@
 
   Symbol* sym = NULL;
   if (name_str != NULL) {
-    sym = SymbolTable::new_symbol(name_str, CHECK_NULL);
+    sym = SymbolTable::new_permanent_symbol(name_str, CHECK_NULL);
   }
   KlassHandle klassklass (THREAD, Universe::typeArrayKlassKlassObj());
 
--- a/src/share/vm/runtime/globals.hpp	Thu Mar 15 13:37:13 2012 +0100
+++ b/src/share/vm/runtime/globals.hpp	Fri Mar 23 11:16:05 2012 -0400
@@ -3807,7 +3807,7 @@
   product(uintx, SharedReadOnlySize,   10*M,                                \
           "Size of read-only space in permanent generation (in bytes)")     \
                                                                             \
-  product(uintx, SharedMiscDataSize,    NOT_LP64(4*M) LP64_ONLY(5*M),       \
+  product(uintx, SharedMiscDataSize, NOT_LP64(4*M) LP64_ONLY(5*M) NOT_PRODUCT(+1*M),       \
           "Size of the shared data area adjacent to the heap (in bytes)")   \
                                                                             \
   product(uintx, SharedMiscCodeSize,    4*M,                                \