Use the Mutex object : Mutex : Thread C# Examples

    
using  System;
using  System.Threading;

class  MainClass
{
    private  static  int  Runs  =  0;

    static  Mutex  mtx  =  new  Mutex(false,  "RunsMutex");

    public  static  void  CountUp()  
    {
        while  (Runs  <  10)
        {
            //  acquire  the  mutex
            mtx.WaitOne();
            int  Temp  =  Runs;
            Temp++;
            Console.WriteLine(Thread.CurrentThread.Name  +  "  "  +  Temp);
            Thread.Sleep(1000);
            Runs  =  Temp;
            //  release  the  mutex
            mtx.ReleaseMutex();
        }  
    }

    public  static  void  Main()  
    {
        Thread  t2  =  new  Thread(new  ThreadStart(CountUp));
        t2.Name  =  "t2";
        Thread  t3  =  new  Thread(new  ThreadStart(CountUp));
        t3.Name  =  "t3";
        t2.Start();
        t3.Start();
    }
}