Question

class OneAtATimePlease
{
    static void Main()
    {

        using (var mutex = new Mutex(false, "oreilly.com OneAtATimeDemo"))
        {
            if (mutex.WaitOne(TimeSpan.FromSeconds(3), false))
                RunProgram();
            else
            {
                Console.WriteLine("Another instance of the app is running. Bye!");
                return;
            }
        }
    }
    static void RunProgram()
    {
        Console.WriteLine("Running. Press Enter to exit");
        Console.ReadLine();
    }
}

but those lines waits for someone to call Set() function :

 if (mutex.WaitOne(TimeSpan.FromSeconds(3), false))
                RunProgram();

who is calling set here ? this thread will never be released…(or will?)

what am i missing ?

Answer 1

WaitOne() immediately returns with a true if someone’s not running it. Else, it blocks! The program which then finishes, causes one of the waiting programs to return with a true immediately.