Would it be possible that you have a deadlock in the
DoSomethingWithAttributes() method. You said you have about 50 Threads.
Maybe some synchronization problem. Do the attributes values go to a
database? Could it be a mutual lock between Java and database (a Thread
locking a Java code block waiting for a value from a DB table locked by
another Thread that in turns needs the locked Java code block... ARG...)

Where's ctls.setTimeLimit(5); ?  That's 5 milliseconds - is that what
you really want? Your doSomething() could be really something like my
doLookup() - proven to work for me:

private Object doLookup (NamingEnumeration results, String type) throws
WSSecurityException
 {
   try
   {
     Fwlog.debug(this, Fwlog.DB, "doLookup...");
     if (results.hasMore())
     {
       SearchResult sr = (SearchResult) results.next();
       javax.naming.directory.Attributes xanswer = sr.getAttributes();
       javax.naming.directory.Attribute attribute = xanswer.get(type);
       // check if attribute missing
       if (null==attribute)
       {
         throw new IllegalStateException("\nERROR: Attribute type not
found: " + type);
       }

       // retrieve attribute as object and return
       Object o = attribute.get();
       if (null == o)
       {
         throw new IllegalStateException("Recieved null object for
attribute type: " + type);
       }

       return o;
     }
     else
     {
       throw new IllegalStateException("Empty Subject recieved");
     }
   }//end try
   catch ( Exception e )
   {
     Fwlog.error(this, Fwlog.DB, "doLookup() failed for for type: " +
type);
     Fwlog.error(this, Fwlog.DB, e);
     throw new WSSecurityException(e.toString(), e);
   }
 }

HTH,
iksrazal
http://www.braziloutsource.com/