C#程序只运行一个实例

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace U_Disk_tool
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            bool runone;
            System.Threading.Mutex run = new System.Threading.Mutex(true, "single_test", out runone);//设置互斥信号量
            if (runone)
            {
                run.ReleaseMutex();
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
            }else{
            MessageBox.Show("Exists");
        }

        }
    }
}