Unload event for the default Application Domain?

Question

Is there an Unload event, or any event, notification, message, mechanism, or hook, that i can use to be notified before the "default" application domain is unloaded?

i have code that needs to know when the application domain (almost always the default domain) is ending.

Note: i don't know what kind of application a developer will be creating when he uses my code. It could be:

a console application
a WinForms application
an ASP.net application
an ASP.net web-site
Runtime Callable Wrapper (RCW) COM object
a Windows Explorer shell extension
or a Windows Service

Either way, i need to know when the domain is closing, so i can do some "stuff". And i am not going to require the user to call any sort of "Shutdown" or "Cleanup" method. (Also, suggesting that the user be required to call a method themselves doesn't answer the question: which is about being notified when the app domain i'm running in is shut down).

So you are building a library that would be consumed by other application and you want to know when the default app domain of those applications is unloaded ? — Ibrahim Najjar
@Sniffer i want to know when the AppDomain that i am in (which 100% of the time will be the default domain) is being unloaded, so i can "shutdown". — Ian Boyd
OK, I understand. Have you looked at AppDomain.ProcessExit. Conceptually that event should also signal the end of the default-AppDomain (and is also raised in the default domain). The total execution time of suche event handlers is limited, however, and the work you try to do sounds rather "involved". YMMV. — Christian.K
It should be noted that AppDomain.ProcessExit won't fire if the process is terminated through, for example, the Task Manager. — Cole Campbell

Ian Boyd Ian Boyd · Accepted Answer · 2013-09-06T18:20:50

i forgot to cross post my own answer from my other slight variation of this question. Ultimately, the answer came from an answer by M.A. Hanin.

There is no DomainUnload, but there is a ProcessExit:

class Contoso
{
   //constructor
   public Contoso()
   {
      //...

      //Catch domain shutdown (Hack: frantically look for things we can catch)
      if (AppDomain.CurrentDomain.IsDefaultAppDomain())
         AppDomain.CurrentDomain.ProcessExit += MyTerminationHandler;
      else
         AppDomain.CurrentDomain.DomainUnload += MyTerminationHandler;
   }

   private void MyTerminationHandler(object sender, EventArgs e)
   {
      //The domain is dying. Serialize out our values
      this.Dispose();
   }

   ...
}

Note: Any code is released into the public domain. No attribution required.

Unload event for the default Application Domain?

See also

2 Answers