How can I prevent launching my app multiple times?

Question

I deployed my C# WinForms application using ClickOnce installation. Everything works fine with it (after a lot of work) :), but now I'm facing a problem:

Whenever I click on the application shortcut in the Start menu, a new instance starts. I need to avoid this.

What can I do to prevent multiple launches?

Answer 1

At program startup check if same process is already running:

using System.Diagnostics;  static void Main(string[] args) {    String thisprocessname = Process.GetCurrentProcess().ProcessName;     if (Process.GetProcesses().Count(p => p.ProcessName == thisprocessname) > 1)       return;            } 

Answer 2

Use this code:

[STAThread] static void Main()  {    using(Mutex mutex = new Mutex(false, "Global\\" + appGuid))    {       if(!mutex.WaitOne(0, false))       {          MessageBox.Show("Instance already running");          return;       }        Application.Run(new Form1());    } } 

from The Misunderstood Mutex