c# - Finally Block Not Running?

Question

Ok this is kind of a weird issue and I am hoping someone can shed some light. I have the following code:

static void Main(string[] args)
{
    try
    {
        Console.WriteLine("in try");
        throw new EncoderFallbackException();
    }
    catch (Exception)
    {
        Console.WriteLine("in Catch");
        throw new AbandonedMutexException();
    }
    finally
    {
        Console.WriteLine("in Finally");
        Console.ReadLine();
    }
}

NOW when I compile this to target 3.5(2.0 CLR) it will pop up a window saying "XXX has stopped working". If I now click on the Cancel button it will run the finally, AND if I wait until it is done looking and click on the Close Program button it will also run the finally.

Now what is interesting and confusing is IF I do the same thing compiled against 4.0 Clicking on the Cancel button will run the finally block and clicking on the Close Program button will not.

My question is: Why does the finally run on 2.0 and not on 4.0 when hitting the Close Program button? What are the repercussions of this?

EDIT: I am running this from a command prompt in release mode(built in release mode) on windows 7 32 bit. Error Message: First Result below is running on 3.5 hitting close after windows looks for issue, second is when I run it on 4.0 and do the same thing.

Answer 1

I am able to reproduce the behavior now (I didn't get the exact steps from your question when I was reading it the first time).

One difference I can observe is in the way that the .NET runtime handles the unhandled exception. The CLR 2.0 runs a helper called Microsoft .NET Error Reporting Shim (dw20.exe) whereas the CLR 4.0 starts Windows Error Reporting (WerFault.exe).

I assume that the two have different behavior with respect to terminating the crashing process. WerFault.exe obviously kills the .NET process immediately whereas the .NET Error Reporting Shim somehow closes the application so that the finally block still is executed.

Also have a look at the Event Viewer: WerFault logs an application error notifying that the crashed process was terminated:

Application: ConsoleApplication1.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Threading.AbandonedMutexException
Stack:
   at Program.Main(System.String[])

dw20.exe however only logs an information item with event id 1001 to the Event Log and does not terminate the process.