Start a new thread from JSP ???

Question

suppose my JSP code is like this,
<%
Obj.heavyProcess();
%>
How can I start a new thread to do
out.println(" ");
out.flush("");
while the heavyProcess is going on? I need to do this because my ISP will cut any Idle connection after certain time and my heavyProcess takes a long time to finish.
for certain reasons, I can not do waiting page, refreshing, etc.

Answer 1

The same way as you would from a normal java application. Write your thread class
package com.yourpkg;
public class YourHeavyProcess implements Runnable{
   private YourObject obj;
   public YourHeavyProcess(YourObject obj){
            this.obj = obj;
   public void run(){
       obj.heavyProcess();
}and create and invoke this thread from your jsp.
<%
        YourObject obj = new YourObject();
        Thread t = new Thread(new YourHeavyProcess(obj));
        t.start();
%>
out.println()..;
out.flush()....;Note that the thread cannot write anything to the output stream as the response is over and done with. It can only perform backend tasks (like data archival for instance)
You could consider using a Timer and a TimerTask class which provides a slightly higher abstraction layer over threads . Look at [url http://forum.java.sun.com/thread.jspa?threadID=758874]this  post (reply 48) for an example.
And finally you wouldnt want a large number of threads to be generated and competing for cpu time on your web server (whose primary responsibility is to receive http requests and send responses). You can use a thread pool to manage the number of threads spawned by your application. If you use java5, take a look at the [url http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/Executors.html]java.util.concurrent.Executor class for thread pool implementations that you can use off the shelf.
cheers,
ram.