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How to prevents many instances of C# program? RRS feed

  • Question

  • How to prevents many instances of C# program?

    After installation, a user can start many windows of C# program on "Start" menu.





    However, I just want it to run one instance, want a user use one window each time.

    How to solve this problem of C#? Can I just config the Visual Studio 2005 to set this option?
    本人现在使用Windows Server 2003, CentOS Linux 5.2, Windows XP, VirtualBox 2.1.4, Visual Studio 2005, Eclipse 3.4, Microsoft.NET Framework 2.0 SP2, C# 2.0, IIS 6.0, Apache 1.3.41, Nginx-0.6.36, SQL Server 2000, MySQL 5.0, FireBird 2.1.2, PHP 5.2.4, Office 2007, OpenOffice 3.0和永中Office2009.
    Tuesday, May 26, 2009 5:03 AM

Answers

  • Hi,
      You can use Mutex class for your requirment. Code as follows.

      Mutex theMutex = null;

      try // Try and open the Mutex
      {
          theMutex = Mutex.OpenExisting("MYMUTEX");
      }
      catch (WaitHandleCannotBeOpenedException)
      {
          // Cannot open the mutex because it doesn't exist
      }

     
      if (theMutex == null)//Application not running
      {
          theMutex = new Mutex(false, "MYMUTEX");
      }
      else
      {
          ///Application Running
      }

    You can also try the follwoing.
        static class Program
        {
            static Mutex mSingleInstance;
            static void Main(string[] args)
            {
                bool createdNew;
                mSingleInstance = new Mutex(false, "Local\\MyProgram", out createdNew);
                if (createdNew)
                {
                    Console.WriteLine("No other instance available");
                    //You can instatiate the applcation from here.
                    Console.ReadLine();
                }
                else
                {
                    Console.WriteLine("Instance Exists");
                    Console.ReadLine();
                }
            }
        }

    -- Thanks Ajith R [Remember to Mark as Answer if it is Helpful.]
    • Proposed as answer by Fernando Nicolet Tuesday, May 26, 2009 5:49 AM
    • Edited by Ajith R Nair Tuesday, May 26, 2009 5:51 AM
    • Marked as answer by dvdvip Tuesday, May 26, 2009 7:19 AM
    Tuesday, May 26, 2009 5:41 AM
  • Nope. You need to write code for achieving this.

    This a common problem and the solution is Single instance application.
    For achieving is you can either use
    1. Mutex, or
    2. Get all process list and check whether process is running or not

    Option1

    static void Main() {
       bool running;
       System.Threading.Mutex mutex = new System.Threading.Mutex(true, "applicationame", out running);
       if(!running) {
          MessageBox.Show("Application is already running");
       }
       Application.Run(new Form1());
       GC.KeepAlive(mutext);
    }

    Option2

    static void Main() {
       Process curr = Process.GetCurrentProcess();
       Process[] procs = Process.GetProcessesByName(curr.ProcessName);
       bool flag;
       foreach (Process p in procs) {
          if ((p.Id != curr.Id) && (p.MainModule.FileName == curr.MainModule.FileName))
             flag=true;
             break;
          }
       }
       if(flag) {
          MessageBox.Show("Application is already running");
       }
       else {
          Application.Run(new Form1());
       }
    }


    Thanks,
    A.m.a.L
    .Net Goodies
    Remember to click "mark as answered" when you get a correct reply to your question
    • Proposed as answer by Fernando Nicolet Tuesday, May 26, 2009 5:50 AM
    • Marked as answer by dvdvip Tuesday, May 26, 2009 7:19 AM
    Tuesday, May 26, 2009 5:41 AM
  • This code actually just prevents from running if there already is a process with the same name. You may want to look further into the Process class.

    static void Main()
    {
        Process existingProcess = Process.GetProcessesByName(current.ProcessName)
            .Where(proc => proc.Id != Process.GetCurrentProcess().Id)
            .FirstOrDefault();
    
        if (existingProcess != null)
            return;
    
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new FrmMain());
    }

    Hope it helps,
    Fernando.
    Keep it Sharp
    • Edited by Fernando Nicolet Tuesday, May 26, 2009 5:50 AM
    • Marked as answer by dvdvip Tuesday, May 26, 2009 7:19 AM
    Tuesday, May 26, 2009 5:48 AM
  • If you inherit the VisualBasic application object instead of the regular C# one it will do all the hard work for you, check out this article on the subject.
    • Marked as answer by dvdvip Tuesday, May 26, 2009 7:19 AM
    Tuesday, May 26, 2009 5:52 AM

All replies

  • Hi,
      You can use Mutex class for your requirment. Code as follows.

      Mutex theMutex = null;

      try // Try and open the Mutex
      {
          theMutex = Mutex.OpenExisting("MYMUTEX");
      }
      catch (WaitHandleCannotBeOpenedException)
      {
          // Cannot open the mutex because it doesn't exist
      }

     
      if (theMutex == null)//Application not running
      {
          theMutex = new Mutex(false, "MYMUTEX");
      }
      else
      {
          ///Application Running
      }

    You can also try the follwoing.
        static class Program
        {
            static Mutex mSingleInstance;
            static void Main(string[] args)
            {
                bool createdNew;
                mSingleInstance = new Mutex(false, "Local\\MyProgram", out createdNew);
                if (createdNew)
                {
                    Console.WriteLine("No other instance available");
                    //You can instatiate the applcation from here.
                    Console.ReadLine();
                }
                else
                {
                    Console.WriteLine("Instance Exists");
                    Console.ReadLine();
                }
            }
        }

    -- Thanks Ajith R [Remember to Mark as Answer if it is Helpful.]
    • Proposed as answer by Fernando Nicolet Tuesday, May 26, 2009 5:49 AM
    • Edited by Ajith R Nair Tuesday, May 26, 2009 5:51 AM
    • Marked as answer by dvdvip Tuesday, May 26, 2009 7:19 AM
    Tuesday, May 26, 2009 5:41 AM
  • Nope. You need to write code for achieving this.

    This a common problem and the solution is Single instance application.
    For achieving is you can either use
    1. Mutex, or
    2. Get all process list and check whether process is running or not

    Option1

    static void Main() {
       bool running;
       System.Threading.Mutex mutex = new System.Threading.Mutex(true, "applicationame", out running);
       if(!running) {
          MessageBox.Show("Application is already running");
       }
       Application.Run(new Form1());
       GC.KeepAlive(mutext);
    }

    Option2

    static void Main() {
       Process curr = Process.GetCurrentProcess();
       Process[] procs = Process.GetProcessesByName(curr.ProcessName);
       bool flag;
       foreach (Process p in procs) {
          if ((p.Id != curr.Id) && (p.MainModule.FileName == curr.MainModule.FileName))
             flag=true;
             break;
          }
       }
       if(flag) {
          MessageBox.Show("Application is already running");
       }
       else {
          Application.Run(new Form1());
       }
    }


    Thanks,
    A.m.a.L
    .Net Goodies
    Remember to click "mark as answered" when you get a correct reply to your question
    • Proposed as answer by Fernando Nicolet Tuesday, May 26, 2009 5:50 AM
    • Marked as answer by dvdvip Tuesday, May 26, 2009 7:19 AM
    Tuesday, May 26, 2009 5:41 AM
  • This code actually just prevents from running if there already is a process with the same name. You may want to look further into the Process class.

    static void Main()
    {
        Process existingProcess = Process.GetProcessesByName(current.ProcessName)
            .Where(proc => proc.Id != Process.GetCurrentProcess().Id)
            .FirstOrDefault();
    
        if (existingProcess != null)
            return;
    
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new FrmMain());
    }

    Hope it helps,
    Fernando.
    Keep it Sharp
    • Edited by Fernando Nicolet Tuesday, May 26, 2009 5:50 AM
    • Marked as answer by dvdvip Tuesday, May 26, 2009 7:19 AM
    Tuesday, May 26, 2009 5:48 AM
  • If you inherit the VisualBasic application object instead of the regular C# one it will do all the hard work for you, check out this article on the subject.
    • Marked as answer by dvdvip Tuesday, May 26, 2009 7:19 AM
    Tuesday, May 26, 2009 5:52 AM