Does C# timers start new thread?

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Hello guys,
I want to know that does C# timers take up new thread or they work on the main thread?
I am having a console app where I have something running or main thread and it takes 4-5 hours. In those 4-5 hours, at every 5 mins I want to run some code. So can I use timer so that it starts new thread and execute while main thread is still running. Or i will have to make thread for timer?

Posted 18-Mar-14 2:19am

Ami_Modi

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OriginalGriff · Answer 1 · 2014-03-18T02:36:00

Solution 2

To be honest, I wouldn't use a timer at all.
Instead, I would set up the code on a BackgroundWorker thread instead, and call Thread.Sleep to pause between runs:

C#

BackgroundWorker work = new BackgroundWorker();
    work.DoWork += new DoWorkEventHandler(work_DoWork);
    work.RunWorkerAsync();
    ...

void work_DoWork(object sender, DoWorkEventArgs e)
    {
    while (true)
        {
        RunYourCodeHere();
        System.Threading.Thread.Sleep(5 * 60 * 1000);  // Wait five minutes
        }
    }

Posted 18-Mar-14 2:36am

OriginalGriff

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Vedat Ozan Oner 18-Mar-14 9:28am

Why?

OriginalGriff 18-Mar-14 9:50am

Timers are expensive resources. If you have a long job, then moving it to a background worker makes it run at a lower priority than "normal" tasks, so even when it does run it has little or no effect on your user - because all his other tasks (inside or outside your application) are running at normal priority and thus "bump" the background worker and run ahead of it.
Not only do timers consume system resources, but they can also generate problems: what happens if you get a timer tick but you haven't completed the previous run yet? If you use a "pause" within the thread that can't happen.

Have a look with google, and you will see there are quite a lot of people who advocate that timers are evil and should never be used!

Don't get me wrong - Timers are very useful, and I use them quite often. But there are times when you are better off not using them.

Vedat Ozan Oner 18-Mar-14 16:54pm

thanks for the explanation. I haven't ever used (thought) backgroundworker as in your sample. this is very useful. but what happens if "RunYourCodeHere" method takes a long time compared to "thread.sleep"? I think the aim determines which technique is better to use.

OriginalGriff 18-Mar-14 17:05pm

Doesn't matter - the thread won't sleep until the RunYourCodeHere returns anyway.

Vedat Ozan Oner 18-Mar-14 17:45pm

yes right but what I try to say is that, for example, I want to run "RunYourCodeHere" for (about) every 5 minutes. but let's say "RunYourCodeHere" takes time between 1-3 minutes. then it runs every 6-8 minutes, not 5 minutes.

OriginalGriff 18-Mar-14 17:55pm

Easy.
Create a DateTime and set it to the end time:
DateTime nextRun = DateTime.Now.AddMinutes(5);
Then run the method.
After it, run a simple loop:
while (nextRun > DateTime.Now) Thread.Sleep(30000);
If you method takes longer than 5 minutes, it'll run again immediately, if not it'll wait till five minutes is up.
(Gawd! I hate typing code on a tablet!)

Ami_Modi 19-Mar-14 3:37am

But what if I dont know end time? I have to perform the job till the database field 'sending_status'has 'sending'. When it changes to 'sent' the background work should stop. How can I do it with your code?

OriginalGriff 19-Mar-14 4:03am

You don't "need" to know the end time: the code above uses the current time, and adds 5 minutes!

OriginalGriff 19-Mar-14 6:46am

Exactly how you stop it is a good question - and one I can't answer. It depends on your code, rather than mine: if you are checking the "sending_status" field in your database as part of the method you are calling in the loop, then I'd just return a true/false value from that method to indicate continue / don't continue and exit the loop (or return from the event handler) if it returns false. If you are checking it elsewhere, then that's up to you - I can't see your code!

Ami_Modi 19-Mar-14 4:05am

U said to create DateTime and set it to end time.

OriginalGriff 19-Mar-14 4:07am

... and then I followed it with an example...

Abhinav S · Answer 2 · 2014-03-18T02:29:00

From msdn documentation [^]-
"System.Threading.Timer is a simple, lightweight timer that uses callback methods and is served by thread pool threads. It is not recommended for use with Windows Forms, because its callbacks do not occur on the user interface thread. System.Windows.Forms.Timer is a better choice for use with Windows Forms. For server-based timer functionality, you might consider using System.Timers.Timer, which raises events and has additional features."

Also, check out this answer[^].