Sneal - Killing System.Process and it's Child Processes

Sunday, October 14, 2007

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Killing System.Process and it's Child Processes

I needed the ability to kill a process and any of its child processes, but System.Process.Kill() does not kill any child processes.

I tried using the JobObjectWrapper library, but unfortunately it doesn't work when running from an existing job, which is exactly the scenario I needed since Visual Studio 2005 on Windows Vista is already running under a job.

The solution I opted for was to use the WindowsXP Pro/Windows Vista taskkill.exe utility since it supports kill a task tree.

/// <summary>
/// Will kill a process and all its child processes.  This class requires
/// taskkill.exe present in the WINDIR\System32 directory.
/// </summary>
public class TaskKill
{
    private readonly int pid;
    private readonly string imageName;
 
    public TaskKill(string imageName)
    {
        this.imageName = imageName;
    }
 
    public TaskKill(int pid)
    {
        this.pid = pid;
    }
 
    /// <summary>
    /// Kills the process associated with this TaskKill instance.
    /// </summary>
    public void KillAssociatedProcess()
    {
        if (!string.IsNullOrEmpty(imageName))
            KillProcessByName();
        else
            KillProcessById();
    }
 
    protected void KillProcessById()
    {
        string killArgs = string.Format("/F /PID {0} /T", pid);
        ExecuteKill(killArgs);
    }
 
    protected void KillProcessByName()
    {
        string killArgs = string.Format("/F /IM {0} /T", imageName);
        ExecuteKill(killArgs);
    }
 
    protected string GetTaskKillExePath()
    {
        string taskKillPath = Path.Combine(Environment.SystemDirectory, "taskkill.exe");
        if (!File.Exists(taskKillPath))
            throw new FileNotFoundException(
                "Cannot find taskkill.exe in the Windows Sytem32 directory.  Are you running WindowsXP Home which doesn't include this utility?");
 
        return taskKillPath;
    }
 
    private void ExecuteKill(string processShellArgs)
    {
        ProcessStartInfo info = new ProcessStartInfo(GetTaskKillExePath(), processShellArgs);
        info.CreateNoWindow = true;
 
        Process process = new Process();
        process.StartInfo = info;
        process.Start();
        process.WaitForExit(5000);
    }
}

The code that uses the TaskKill class looks like this:

[Test]
public void Test1()
{
    ProcessStartInfo info = new ProcessStartInfo("notepad.exe");
    Process process = new Process();
    process.StartInfo = info;
    process.Start();
 
    Assert.That(!process.HasExited, "Process exited early");
 
    TaskKill taskKill = new TaskKill(process.Id);
    taskKill.KillAssociatedProcess();
 
    Assert.That(process.HasExited, "TaskKill failed to kill the process");
}