Concurrent database access pattern for web applications

I'm trying to write a Spring web application on a Weblogic server that makes several independent database SELECTs(i.e. they can safely be called concurrently), one of which takes 15 minutes to execute.

Once all the results are fetched, an email containing the results will be sent to a user list.

What's a good way to get around this problem? Is there a Spring library that can help or do I go ahead and create daemon threads to do the job?

EDIT: This will have 开发者_StackOverflow中文版to be done at the application layer (business requirement) and the email will be sent out by the web application.

1. Are you sure you are doing everything optimally? 15 minutes is a really long time unless you have a gabillion rows across dozens of tables and need a heckofalot of joins....this is your highest priority -- why is it taking so long?

2. Do you do the email job at set intervals, or is it invoked from your web app? If set intervals, you should do it in an outside job, possibly on another machine. You can use daemons or the quartz scheduler.

3. If you need to fire this process off from the web app, you need to do it asynchronously. You could use JMS, or you could just have a table into which you enter a new job request, with daemon process that looks for new jobs every X time period. Firing off background threads is possible, but its error prone and not worth the complication, especially since you have other valid options that are simpler.

If you are asking about Spring support for long-running, possibly asynchronous tasks, you have a choice between Spring JMS support and Spring Batch.

You can use spring quartz to schedule the job. That way the jobs will run in the same container but will not require an http request to trigger them.