With Tomcat 7.0.42 and the NIO connector, calling AsyncContext.dispatch() from an onTimeout() handler fails with this error message:

jul 31, 2013 1:40:30 PM org.apache.coyote.AbstractProtocol$AbstractConnectionHandler process
SEVERE: Error reading request, ignored
java.lang.IllegalStateException: Calling [asyncPostProcess()] is not valid for a request with Async state [STARTED]
        at org.apache.coyote.AsyncStateMachine.asyncPostProcess(AsyncStateMachine.java:204)
        at org.apache.coyote.AbstractProcessor.asyncPostProcess(AbstractProcessor.java:116)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:593)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1690)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:724)


Test code:

public class AsyncServlet extends HttpServlet {

  protected void doGet(final HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {

    if (request.isAsyncStarted()) {
      response.getWriter().write("asyncResult=" + request.getAttribute("asyncResult"));
    }
    else {
      final AsyncContext asyncContext = request.startAsync(request, response);

      asyncContext.addListener(new AsyncListener() {
        public void onTimeout(AsyncEvent event) throws IOException {
            request.setAttribute("asyncResult", "timeout\n");
            asyncContext.dispatch();
        }
        public void onStartAsync(AsyncEvent event) throws IOException {}
        public void onError(AsyncEvent event) throws IOException {}
        public void onComplete(AsyncEvent event) throws IOException {}
      });

      asyncContext.setTimeout(5000L);
    }
  }

}


This seems somewhat similar to the (ancient) report #50308.