asp.net - What are some best practices for managing background threads in IIS?

Question

I have written an HttpModule that spawns a background thread. I'm using the thread like a Scheduled Task that runs in-process, which is really handy.

What are best practices for keeping track of this thread? I've never done this before, and I'm a little confused about some aspects of it:

1. How do I know if the thread is still running? I see it do its job, but is there another way to know if it's still alive? I downloaded ProcMon, but w3wp.exe spawns a boatload of threads, so I had no idea which was my thread. I named it, but that didn't help.

2. How do I "catch" the thread if it dies? Is there some kind of Dispose method where I can have it write to the EventLog or something if it fails? A "dying declaration" or something?

3. How do I actively stop the thread? If I want it to stop running this background process, how do I kill it without having to bounce IIS?

4. Is there anyway to start it again, independently of the HttpModule? (I'm guessing the answer to this is no...)

Edit: Just to clarify, the intention is that my thread never goes away. It runs a function, then goes to sleep for a couple minutes, then wakes up and runs the function again. It's not like it's doing one task then ending.

Answer 1

When Jeff made Stackoverflow, he had a similiar issue.

His solution was to use the cache expiration. You'd put something in the cache and then when it expires an event is fired in a non-user facing thread. In the event handler for the expiration, you stick some code in to re-add the item to the cache and do whatever housekeeping work needs to be done for your application

Using this technique, your subquestions are easily answered:

1. You check the item is still in cache.
2. If the item is not in cache, re-add it.
3. Remove the cache item from the cache.
4. Add the item back to the cache.

You could make a small management page to configure these options.

This gives you a nice way to roughly time housekeeping processes in your web-application. It doesn't require a seperate Windows Service, which is a big win.