Question

I’m new to programming. I have a form application that launches a thread. Form there 4 new threads are launched. Each of these threads performs a series of command line processes like the following:

ProcessStartInfo startInfo = new ProcessStartInfo();
        startInfo.WorkingDirectory ="C:\\BLA\\bin_windows";
        startInfo.UseShellExecute = false;
        startInfo.RedirectStandardOutput = true;
        startInfo.CreateNoWindow = true;

            startInfo.FileName = "SomeProcess"
            Process p = Process.Start(startInfo);
        p.WaitForExit();

When the form application is closed it aborts the first thread (not the 4 separate ones).
Now my question is how to force the processes “p” to quit when I close the form??
I tried the following:

    foreach (Process p in System.Diagnostics.Process.GetProcessesByName("SomeProcess"))
    {
        try
        {
            p.Kill();
            p.WaitForExit(); // possibly with a timeout
        }
        catch
        { continue; }
    } 

However, this approach seems a little brutal to me and does not always work well… Is there a way that I can identify only the processes that Ive launched myself and then terminate them?
Any suggestions greatly appreciated.
Thanks

Answer 1

You have very little control of processes you have run. Killing them is one way. If the process is a windowed application (i.e. has a window) you can try sending it a WM_CLOSE message which is equivalent of clicking a close button on the window. Again, application must have a window, either visible or hidden and because of that it will not work on every application. Most applications do have windows though even if not visible.

const uint WM_CLOSE = 0x10;

[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern int SendMessage(IntPtr hWnd, uint uMsg, int wParam, int lParam);

Process p = Process.GetProcessesByName("notepad").FirstOrDefault();
if(p != null)
{
    IntPtr hWnd = p.MainWindowHandle;
    SendMessage(hWnd, WM_CLOSE, 0, 0);
}

To kill/close only processes you have spawned just keep their Process objects or at least p.MainWindowHandle if you want to use approach I gave you. For that, have a public property of type ConcurrentBag<Process> (or ConcurrentBag<IntPtr>) in your class. It is already thread safe.

EDIT

As someone pointed out you can do this to close process’ main window:

p.CloseMainWindow()