Why a thread is aborted in ASP.NET MVC (again)?

Question

Here is what I do in a controller action:

1. create and start a new Thread that does a relatively long processing task (~30 seconds on average, but might be several minutes)
2. immediately return the page response so the user knows processing has started (trivially, a Json with a task ID for polling purposes).

At some random point, ThreadAbortException is thrown, so the async task does not complete. The exception is not thrown every time, it just happens randomly roughly 25% of the times.

Points to note:

• I'm not calling Response.End or Response.Redirect - there isn't even a request running when the exception is thrown
• I tried using ThreadPool and I got the same behavior
• I know running threads in ASP.NET has several caveats but I don't care right now

Any suggestion?

Answer 1

The problem is you shouldn't do it this way. If you need a task to run for a long period of time in the background ASP.Net should either spawn a process to handle it or add the work item to a queue for a Windows Service to handle.

Answer 2

Does this help since you want to fire and forget.

"Delegates provide a method called BeginInvoke that allows us to call the delegate asychronously."

http://hackingon.net/post/Asynchronous-fire-and-forget-method-calls-in-NET.aspx

Answer 3

How about using an Asynchronous controller?

Answer 4

The problem was that the app was being recycled. I perfectly know that when that happens, all threads are aborted, I didn't expect the application to recycle. The reason is that the async process used changed temp files stored in the app root, and that caused a recycle.

I feel dumb.