Just when you think it's safe to go back in the water

Microsoft development libraries and tools have been around a long time and it's easy to think that all the kinks have been worked out. If weird stuff happens it's got to be in my code…right? Wrong.

I spent several days trying to figure out why, when I stepped (F10) over an instruction…I lost my thread. I thought of everything that could go wrong: GC, aborted thread, ThreadPool starvation, etc… I tried a lot of stuff.

A word of debugging advice, whenever you find yourself in a messy situation, try to find the simplest setup that produces the problem. I stripped my code down to:

public partial class frmMyForm : Form
{
    private void frmFonBook_Shown(object sender, EventArgs eArgs)
    {
        ThreadPool.QueueUserWorkItem(new WaitCallback(_DoSomething), this);
    }
}

static void _DoSomething(Object state)
{
    frmMyForm frmObject = state as frmMyForm;
    if (frmObject != null )
    {
        frmObject.MakeACall();
    }
} 

Eventually I hit on the right search terms and came up with this link. There are some other links in the post that explain things in more detail here and here. It's a crazy world but the IDE was actually the problem NOT my code.

Basically to get around this probem open VS2005, select Tools->Options->Debugging->General and then disable the 'Enable property evaluation and other implicit function calls' checkbox.

So here are some search terms that I hope will make someone else's life easier:

disappearing thread
collected thread object
lost
failed step
IDE broken