Hi,
Thread.join() can be very interesting and have non-obvious behavior in a servlet.
Here's a simple alternative design:
public class MyReportJob implements Runnable
{
private boolean done = false;
...
public void run()
{
... do work ...
done = true;
}
public boolean isDone()
{
return done;
}
}
Then, in your servlet:
Runnable myReportJob = new MyReportJob();
Thread myReportThread = new Thread(myReportJob);
myReportThread.start();
while(! (myReportJob.isDone()))
{
... wait ...
}
And when you get here, you're done with the job and
can present its results.
So the question is, if you're waiting for a thread anyways, why not just do the work
in the servlet itself and make the code simpler? There are several advantages (but
also at least one disadvantage) to the above:
- You can present a "please wait, I'm doing work" graphic or whatever to the user
while the thread is running.
- You can place a time bound on the thread
- You can use a thread pool with pre-allocated report creation threads to improve
performance
- You're separating the processing logic for report creation from the servlet or JSP
presentation of the report results (to some extent)
Still, it may be better to go a little further and have a Singleton or Factory for
reports. You would just specify the params and let that singleton worry about thread
creation etc. This could be a useful Façade if you decide to eventually have the
report creation done elsewhere (e.g. another server)....
Like most design questions, there are a lot of ways to go on this one ;)
Yoav Shapira
Millennium ChemInformatics
Yoav Shapira
Millennium ChemInformatics
>-----Original Message-----
>From: Phillip Rhodes [mailto:rhodespc@;telerama.com]
>Sent: Sunday, October 27, 2002 1:01 PM
>To: [EMAIL PROTECTED]
>Subject: start new thread from servlet?
>
>Sorry, I searched and searched for four hours all over the place and have
>not found a definitive how-to or example.
>Sorry if this is off-topic...
>
>In my servlet, I will be running long reports. I want to kick off a new
>thread that will run the report.
>I read somewhere that I have to join my new thread to the thread of my
>servlet to avoid problems.
>
>Can anyone point me to a how-to on this?
>Thanks!
>
>Phillip
>
>
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