ServletContextListener and Starting a Thread

[Brian Hart]

I'm looking to 'poll' a database table for new records. I want to have a low priority thread check a database table while the server is running. the run() method of the Runnable would look something like this:

while(true)
    {
      try{
        ...
        Check Table for rows using JDBC
        ...
      }catch(DataAccessException exc)
      {
        log.fatal("Error attempting to poll database", exc);
      }
      try
      {
        Thread.sleep(1000000);
      }
      catch( InterruptedException ex )
      {
        log.fatal("Thread Issue in Polling",  ex );
      }
    }

I thought that calling this process from within the contextInitialized(ServletContextEvent event) of a ServletContextListener would be an appropriate place to begin this process. However, on Oracle's OC4J J2EE server, I'm getting the message:
Exception thrown initializing batch completed listener: java.lang.Exception: Not in an application scope - start Orion with the -userThreads switch if using user-created threads
The fact that the server by default discourages user created threads makes me think my approach is a bad one.
Two questions:
1. What is a relatively straightforward approach to implement a simple polling thread on a JSP/Servlet based web application (no EJB, JMS).
2. What are the implications of enabling userThreads on Orion.
Thanks in advance.