Cannot evaluate expression because a native frame is on top of the call stack

Question

I'm creating a simple window service and when I go to debug I get the error, "Cannot evaluate expression because a native frame is on top of the call stack.". Also, when I build the service in Release and run it just hangs.

 static void Main()
    {
        ServiceBase[] ServicesToRun;
        ServicesToRun = new ServiceBase[] { new MyService1() };

        ServiceBase.Run(ServicesToRun);
    }

Thats all that is in the Program.cs file, where it normally gets hung on the ServiceBase.Run(ServicesToRun) line.

Everything I've been able to find only relates to the expression not being evaluated because the code is optimized or having to deal with asp.net and response.redirect.

Code for the Service.

    public TruckRateClearService()
    {
        InitializeComponent();
    }

    protected override void OnStart(string[] args)
    {
        tmrProcess.Enabled = true;
    }

    protected override void OnCustomCommand(int command)
    {
        base.OnCustomCommand(command);
        if (command == 129)
        {
            OnStart(null);
        }
    }

    protected override void OnStop()
    {
        tmrProcess.Enabled = false;
    }

    private void tmrProcess_Tick(object sender, EventArgs e)
    {
        tmrProcess.Enabled = false;

        try 
        {
            eventLog.WriteEntry("Clearing Truck Rates Start" + DateTime.Now.ToString());

            TruckRateClearingAgent.Process();

            eventLog.WriteEntry("Clearing Truck Rates Finished" + DateTime.Now.ToString());
        }
        catch (Exception ex)
        {
            eventLog.WriteEntry(ex.ToString(), EventLogEntryType.Error);
        }

        tmrProcess.Enabled = true;
    }

    internal void Run()
    {
        tmrProcess_Tick(tmrProcess, null);
    }

The Internal Void Run() was added just recent on the suggestion in the comments by Eren Ersönmez. His idea has been very helpful for helping debug my logic until I can figure the rest out.

I was able to get the into the Native call stack and it sits on one location, 76F17094 ret. Now I have no idea what this is but maybe someone else will.

Also, when I start the service and look into attaching it to VS I'm noticing two instances of it. One is the normal .exe and another is a .vshost.exe. When I start other services I only see the .exe file in the Attach to process part of the debugger. Could this be because one is on the v4 Framework ( .vshost .exe service ) and another on the v2 ( single .exe service ) Framework?

I believe I got it working. It seems that the problem lied with the timer I was using. The original timer I was using was a System.Windows.Forms timer. I switched it to System.Timers.Timers and everything started working again. Still cant attach VS to it but I can debug it still by using the Internal Run() method. Thanks for all the help n.n

Answer 1

Your main problem is that you're trying to directly run a windows service exe. Windows services can only be started via Service Control Manager (SCM). In order to be able to debug in VS, I'd recommend something like this:

static void Main()
{
    if (Environment.UserInteractive)
    {
        new MyService1().Run();
        Thread.Sleep(Timeout.Infinite);
    }
    else
    {
        ServiceBase.Run(new ServiceBase[] { new MyService1() });
    }
}

You'd create a MyService1.Run method which spawns a new thread that runs the service loop. Also, you'd call the same Run method from within the MyService1.Onstart.

This scheme runs it as a service when being started by SCM, but treats it like a normal exe when being debugged in VS (or being run directly as an exe outside VS).