How to handle Jetty exception - a long running HTTP request times out, but the process it calls never terminates and Jetty is unhappy

I have a Jetty server handling long running HTTP requests- the responses are generated by an a different process X and end up in a collector hash which Jetty requests periodically check.

There are 3 cases:

1. Process X finishes before the timeout period of the HTTP request - no problem
2. Process X finishes after the timeout period of the request - no problem
3. Process X never finishes - below exception occurs

How do I detect this situation (3) and prevent the exception while allowing the other two cases to properly work?

Exception:

2012-06-18 00:13:31.055:WARN:oejut.QueuedThreadPool:
java.lang.IllegalStateException: IDLE,initial
    at org.eclipse.jetty.server.AsyncContinuation.complete(AsyncContinuation.java:569)
    at server.AsyncHTTPRequestProcessor.run(AsyncHTTPRequestProcessor.java:72)
    at org.eclipse.jetty.server.handler.ContextHandler.handle(ContextHandler.java:1119)
    at org.eclipse.jetty.server.AsyncContinuation$1.run(AsyncContinuation.java:875)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:599)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:534)
    at java.lang.Thread.run(Thread.java:679)

Jetty continuation of an HTTP request:

public class AsyncHTTPRequestProcessor implements Runnable {

    private ConcurrentHashMap<String, String> collector;
    private Logger logger;
    private AsyncContext ctx;
    //Defined this here because of strange behaviour when running junit
    //tests and the response json string being empty...
    private String responseStr = null;

    public AsyncHTTPRequestProcessor(AsyncContext _ctx, 
            ConcurrentHashMap<String, String> _collector, Logger _logger) {
        ctx = _ctx;
        collector = _collector;
        logger = _logger;
    }

    @Override
    public void run() {

        logger.info("AsyncContinuation