Hi Sreenivas
U should avoid using threads in servlets and JSP.
But in one scenario threads are useful.
Suppose u have an Request which takes lot of time to process(for e.g an execution of procedure)
then u can execute that procedure in a
thread and return reponse to the request .
This will prevent Browser Timeout to occur.
After u finish executing procedure u can set an attribute in session and return the reponse u wanted to send.
hope this is useful to u.
Bye