System.Threading.Timer class, How it works

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I have following code in console application.
Now if i run it shows '11/11/2013' as output.
But if i make comment line no. 9 (System.Threading.Thread.Sleep(1000);) the same program shows nothing. As per my knowledge TimerTask() should have been called.
Why it depends on 'System.Threading.Thread.Sleep(1000)' for calling TimerTask().

C#

class Program
    {
        static void Main(string[] args)
        {
 System.Threading.TimerCallback TimerDelegate =
                new System.Threading.TimerCallback(TimerTask);
System.Threading.Timer TimerItem =
                new System.Threading.Timer(TimerDelegate, null, 0, 2000);
System.Threading.Thread.Sleep(1000);
}
 private static void TimerTask(object StateObj)
        {
           Console.WriteLine(DateTime.Now.ToString());
}

Posted 11-Nov-13 2:02am

Brijesh Kr

Updated 11-Nov-13 2:06am

v2

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CPallini 11-Nov-13 8:16am

Well, that means that program termination happens 'more immediately' than the timer execution. :-)

Brijesh Kr 11-Nov-13 8:25am

suppose i write 10 or 20 Console.WriteLine("test") after new System.Threading.Timer(TimerDelegate, null, 0, 2000); and comment Sleep(1000). TimerTask() might be called since here i have given main thread change to be alive. Right?

CPallini 11-Nov-13 8:39am

'Might'. That is, the I/O operations give a chance to the timer.

Brijesh Kr 11-Nov-13 8:53am

Hmmmm, if you write Console.ReadLine();
Do me one favor please delete solution 2.

CPallini 11-Nov-13 13:00pm

if you write Console.WriteLine too (please try yourself).

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OriginalGriff · Answer 1 · 2013-11-11T02:12:00

Solution 1

Why?
Why do you think that a thread should be executed if the application it is part of has been terminated?

If you take out the Sleep(1000) then the Main method immediately ends and the application is terminated. At that point, all threads associated with the application are terminated as well. So even if the thread did get a slight chance of running (on a different core perhaps) there isn't time for the console output to be updated before it too is closed down.

Posted 11-Nov-13 2:12am

OriginalGriff

Comments

Brijesh Kr 11-Nov-13 8:17am

System.Threading.Timer(TimerDelegate, null, 0, 2000); Here the 3rd argument is duetime which is set to 0, the thread should start immediately. Right?

OriginalGriff 11-Nov-13 9:28am

Well...yes...but...

What actually happens is that the thread goes into a queue of available-to-run threads that the system maintains - and if it gets the the head of the list and there is a core available in time then it will run. But...your main method doesn't do much, so it won't use up it's "slot" before it finishes adding the new thread to the systems list. So it terminates, and the new thread is also killed at the same time before it really gets a chance to run.

Just because a thread can run, doesn't mean it will - it has to "jostle" with all the other threads that are waiting for a slot to run in before it gets a go.

agent_kruger · Answer 2 · 2013-11-11T03:12:00

the 9th line will execute after 2 sec as you have written

"System.Threading.Timer TimerItem = new System.Threading.Timer(TimerDelegate, null, 0, 2000);"

and your program will get closed in just 1 second as you have called

"System.Threading.Thread.Sleep(1000);"

if you call 9th line multiple time like this

class Program
    {
        static void Main(string[] args)
        {
            System.Threading.TimerCallback TimerDelegate =
                new System.Threading.TimerCallback(TimerTask);
            System.Threading.Timer TimerItem = new System.Threading.Timer(TimerDelegate, null, 1, 4000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
            System.Threading.Thread.Sleep(1000);
        }

        private static void TimerTask(object StateObj)
        {
            Console.WriteLine(DateTime.Now.ToString());
        }
    }

it will show result

NOTE:your program will close as the last "Thread.Sleep" would be executed