DWR

Also, the executor in PurgingDownloadManager stays around, and the field is protected so we can't shut it down from a listener.

As discussed on the mailing list, I think it is very important for drop-in compatibility with 2.0 that DWR 3 doesn't require an extra Listener to shutdown cleanly for non-reverse-Ajax applications. So there should also be shutdown code in Servlet.destroy().

DefaultScriptSessionManager creates non-daemon thread. see - http://java.sun.com/javase/6/docs/api/java/util/concurrent/ThreadPoolExecutor.html this will cause tomcat to hang. i believe this could be fixed by;

public class DaemonThreadFactory implements ThreadFactory {
public Thread newThread(Runnable r) { Thread t = new Thread(r); t.setDaemon(true); return t; }
}

....

ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(1, new DaemonThreadFactory());

i'm not sure where all the changes that need to be made to implement this.

The thread is non-daemon but DWR does not create a ScheduledThreadPoolExecutor. DWR overrides it with org.directwebremoting.impl.AutoShutdownScheduledThreadPoolExecutor which is supposed to handle the shutdown - if the DwrListener is registered.