Question

To help with performance of the clients, I offload the processing of a request onto a task. This is done because the processing usually takes a bit of time, and I don’t want the clients to be waiting for a while just to get the 200 response. The web service that offloads the work onto a task is always processing posts.

public void ProcessRequest(HttpContext context)
{
    // check for bad requests -- return 400

    // get copy of the context input stream

    Task.Factory.StartNew(() =>
    {
        ProcessRequest(contextInputStreamCopy);
    });
}

private void ProcessRequest(Stream inputStream)
{
    try
    {
        // process input stream
    }
    catch(Exception ex)
    {
        // any server error that would normally result in 500 response are not
        // exposed to the clients, the clients are to see 200 when the server 
        // encounters an error
    }
}

So my question is what happens to these tasks when IIS recycles, or when the web site is being stopped.

Answer 1

When IIS recycles, it waits for all that threads to finish and exits – up to the timeout value that have on pool. After that time out they kills all running threads and start again.

So you may set a signaling to your threads to stop when the application request to shut down at globa.asax using the Application_End functions.