title: Application_End and background processes, exiting ASP.Net application gracefully
body: <p>I have an ASP.Net application which fires off some background workers using ThreadPool.QueueUserWorkItem(). Most of the time there will be zero background threads running, however it's possible that there could occationally be up to 5-6 executing at a time. Additionally, most will complete within a couple seconds, but it is possible that they could run for as long as 10 minutes. </p>
  
  <p>Given all the different scenarios that could cause a shutdown of an ASP.Net application, I'd like to have these background processes exit gracefully if possible when the application needs to shutdown and they are in the middle of processing. </p>
  
  <p>I don't anticipate having too much of an issue creating a way to signal the processes to stop their work early and clean up within a few seconds of getting the call that the application is being shut down. Although if anyone has specific advice on this I'd certainly appreciate it.</p>
  
  <p>My two main questions are:</p>
  
  <p>1) When would be the appropriate time to tell the background workers to wrap things up. During Application_End? Dispose()? Or perhaps a third option I'm not aware of.</p>
  
  <p>2) If I wait during the above event for the processes to finish before returning, is there a point where not having Application_End return immediately could cause more serious issues for the application than not shutting down the background jobs nicely.</p>
  
  <pre><code>void Application_End(object sender, EventArgs e) 
  {
      //if this for whatever reason takes a non-trivial time to execute, what problems could I encounter? 
      SignalBackgroundJobsAndWaitForThemToShutDown();
  }
  </code></pre>
  
  <p>Thanks!</p>