Multithreading a jsp?

I'm new to jersey, jsp's and web application development in general so hopefully this isn't a silly question. I've got a jsp and currently when the user hits a button on it, it starts a HTTP request which takes about 5-10 minutes to return. Once it finishes they're redirected to another page.

I'm wondering, is it possible or even advisable that I multithread the application so that the heavy processing will start but the user get's redirected to the next .jsp right away. I开发者_如何转开发f multithreading is not possible is there another method that you would recommend for dealing with heavy processing in a web application?

A JSP is basically a Servlet (it's translated in a Java Servlet Class and compiled). Teoretically you can start a new thread in a servlet (and hence in a JSP, via scriptlet), but that's really not advised for multiple reasons.

It'd be better recommended to make an asynchronous HTTP call via ajax, then, once the call is done immediately show something else to the user, and when the call back returns display the results.

Rather than create a new thread each time it might be more efficient to have a worker thread which continually polls a shared queue. Using, for example, ArrayBlockingQueue you web request can simple add an object to the queue and return to the user, and your worker thread (or repeating scheduled job) can take care of the heavy weight processing.

Instead of waiting for process to complete in a JSP, you can create a TimerTask (or Quartz Job) and set it for immediate execution and redirect user to some other page. Have that Job store the result in some central place that can be accessed by another JSP (in case you want to pull result of Job later, may be through ajax) Doing so, you save yourself from managing threads manually (which is error prone), you get async functionality, user does not need to see the blank browser screen for around 5-10 minutes.

It is possible.

Create a thread, store its reference somewhere that is available everywhere (a static Map) and store its key (in the session, in the code of the JSP's answer).

Following calls can retrieve the thread and check its state/results.

Anyway, use with care:

a) You will need to control that old results are deleted. It is inevitable that sometimes the browser will close, so you need a Watchdog to clear data obviously no longer needed.

b) The user are not used to this kind of behavior. There is a serious risk that they will just "go back" and try to launch the thread again, and again, and again. Try to control it (ideally the id of the thread will be linked to the user, so as long as an older thread is active an user cannot launch another one).