Question

When someone uses the Task Manager to end a .NET process which has instantiated a COM object, AFAIK there is no way to call Marshal.FinalReleaseComObject in a try {} finally {}, using {} or event handling block.

The next time I fire up the application, the COM object is in an unusable state and I need to reboot the machine to make it work again.

I use Marshal.BindToMoniker to instantiate the object.

What am I doing wrong, is there anything I missed?

---

I tried Saeed’s suggestion but it didn’t work

private const int WM_CLOSE = 0x0010;

protected override void WndProc(ref Message m)
{
    if (m.Msg == WM_CLOSE)
    {
        logger.Info("WM_CLOSE");
        Marshal.FinalReleaseComObject(comObject);
    }

    base.WndProc(ref m);
}

Answer 1

Task Manager is using the native equivalent of Process.Kill (or possibly something even stronger). Note this narrative from the documentation:

Kill forces a termination of the process, while CloseMainWindow only requests a termination.

…

Calling CloseMainWindow sends a request to close to the main window, which, in a well-formed application…

And,

Data edited by the process or resources allocated to the process can be lost if you call Kill. Kill causes an abnormal process termination and should be used only when necessary.

In short, there’s nothing you can really do from inside your program code to protect against this – the plug has been pulled. No window messages are going to be sent.