I am trying to prevent my program from running multiple instances at any given time. I have read about using mutex and windows events, however both threads were several years old, and I'm curious if with .net4 there is a more simple, and more elegant way to deal with this? I thought I had read about a setting for the form that allowed you to deny multiple instances by the property? Could someone shed some light on what the safest and/or simplest way to prevent multiple instances of a program is?
The safest way is to use the built-in support in .NET, WindowsFormsApplicationBase.IsSingleInstance property. Hard to guess if it is appropriate, you didn't make much effort describing your exact needs. And no, nothing changed in the past 5 years. – Hans Passant Jan 7 at 0:38
This was the best answer but Hans didn't submit it as an answer.
In VB you can set this at the project level (Properties > General) for Winforms projects.
In C# you can use code similar to this.. needs conversion of course..
Dim tGrantedMutexOwnership As Boolean = False
Dim tSingleInstanceMutex As Mutex = New Mutex(True, "MUTEX NAME HERE", tGrantedMutexOwnership)
If Not tGrantedMutexOwnership Then
'
' Application is already running, so shut down this instance
'
Else
'
' No other instances are running
'
End If
Whoops, I forgot to mention that you will need to place GC.KeepAlive(tSingleInstanceMutex)
after your Application.Run() call
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Windows.Forms;
namespace YourNameSpaceGoesHere
{
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
if (Process.GetProcessesByName("YourFriendlyProcessNameGoesHere").Length > 1)
{
MessageBox.Show(Application.ProductName + " already running!");
Application.ExitThread();
}
else
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new YourStartUpObjectFormNameGoesHere());
}
}
}
}
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