6845161: Bottleneck in Configuration.getConfiguration synchronized call

Summary: Reduce scope of synchronized block
Reviewed-by: weijun

src/share/classes/javax/security/auth/login/Configuration.java

 /*
- * Copyright 1998-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 1998-2009 Sun Microsystems, Inc.  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
@@ -234,12 +234,13 @@ public abstract class Configuration {
      *
      * @see #setConfiguration
      */
-    public static synchronized Configuration getConfiguration() {
+    public static Configuration getConfiguration() {
 
         SecurityManager sm = System.getSecurityManager();
         if (sm != null)
             sm.checkPermission(new AuthPermission("getLoginConfiguration"));
 
+        synchronized (Configuration.class) {
             if (configuration == null) {
                 String config_class = null;
                 config_class = AccessController.doPrivileged
@@ -285,6 +286,7 @@ public abstract class Configuration {
             }
             return configuration;
         }
+    }
 
     /**
      * Set the login <code>Configuration</code>.