Question

I have a somewhat simple Client/Server solution running over C# remoting (System.Runtime.Remoting).

The MarshalByRef object, which is used for the actual communication, however troubles me.

In its constructor it starts up an external process and adds the OutputDataReceived eventhandler.

Every 2 seconds the process will write data to its stdout, which I then retrieve in my eventhandler and use there.

Now my problem is how to cleanup after this process – the thing is, it runs indefinitely so I have to call Kill() on it to stop it.

I tried doing this in the MarshalByRef object’s finalizer, however this caused my application to hang every now and then, when trying to call the finalizer.

The remoting is setup as a Singleton, so it should be the server side which calls the finalizer, so frankly I find it a bit odd it doesn’t work.

The class that spawns the process is actually a field of my MarshalByRef object, but that really shouldn’t change a lot.

Also the class is run in mono on a linux server, and reads out CPU load from the tool mpstat.

Here’s the class which troubles me:

internal class CpuInfo
{
    private Regex parser = new Regex(@"\d{2}:\d{2}:\d{2}\s+(?<CpuID>\d{1,2}).*?(?<IdlePercentage>\d{1,2},\d{1,2})(\r|\n|$)", RegexOptions.Compiled | RegexOptions.Multiline);
    private Process proc;
    private IDictionary<int, long> cpuLoads;
    internal CpuInfo()
    {
        cpuLoads = new Dictionary<int, long>();
        proc = new Process();
        proc.StartInfo.UseShellExecute = false;
        proc.StartInfo.CreateNoWindow = true;
        proc.StartInfo.Arguments = "-u -P ALL 2";
        proc.StartInfo.FileName = "mpstat";
        proc.StartInfo.RedirectStandardOutput = true;
        proc.EnableRaisingEvents = true;
        proc.OutputDataReceived += proc_OutputDataReceived;

        proc.Start();
        proc.BeginOutputReadLine();
    }

    void proc_OutputDataReceived(object sender, DataReceivedEventArgs e)
    {
        Match match = parser.Match(e.Data);
        if (match.Success)
        {
            int cpuID = int.Parse(match.Groups["CpuID"].Value);
            string idleValue = match.Groups["IdlePercentage"].Value.Replace(',', '.');
            decimal idle = decimal.Parse(idleValue, CultureInfo.InvariantCulture);
            cpuLoads[cpuID] = (long)((100m - idle) * 100);
        }
    }

    ~CpuInfo()
    {
        proc.OutputDataReceived -= proc_OutputDataReceived;
        proc.Kill();
    }
}

Answer 1

Figured it out myself now – I use RemoteServices.Marshal serverside and RemoteServices.Connect clientside. This way my object reference exists serverside, and I can use IDisposable to cleanup nicely.