CODEWITHSUNDEEP
c#timer
Amc_rtty
Amc_rtty

Reputation: 3803

System.Timers.Timer delay hangs application

I have an issue with the System.Timers.Timer object. I use the timer object to perform a task at regular intervals. In the timer constructor I call the method doing the work ( DoTimeCheck() ), to ensure that the task is run once at startup also. The work (at regular intervals) is done in a BackgroundWorker.

I call the timer with this:

 UpdaterTimer ut = UpdaterTimer.UpdaterTimerInstance;

My problem is that I need to delay the first run of the task with 3 minutes(the one that runs at application startup). Subsequent runs (Elapsed event) should run without delay. I thought of doing this by calling 

System.Threading.Thread.Sleep(TimeToDelayFirstRunInMiliseconds);

but this fails, because it also hangs the UI of the app (main thread) making it unusable. How can I delay the first run of DoTimeCheck() without hanging the UI? The code of the timer is below. If the issue is not presented in a clear manner please let me know and I will edit. Thank you in advance.

  public sealed class UpdaterTimer : Timer
{
    private static readonly UpdaterTimer _timer = new UpdaterTimer();
    public static UpdaterTimer UpdaterTimerInstance
    {
        get { return _timer; }
    }

    static UpdaterTimer()
    {
        _timer.AutoReset = true;
        _timer.Interval = Utils.TimeBetweenChecksInMiliseconds;
        _timer.Elapsed += new ElapsedEventHandler(_timer_Elapsed);
        _timer.Start();
        DoTimeCheck();

    }

    static void _timer_Elapsed(object sender, ElapsedEventArgs e)
    {
        DoTimeCheck();
    }

    private static void DoTimeCheck()
    {
        //... work here 
    }
}

Upvotes: 1

Views: 3498

Answers (7)

Chris
Chris

Reputation: 27599

You're already using timers fine it seems. Just use another one to do a three minute delay before you start up your other timer.

timer = new Timer();
timer.AutoReset = false;
timer.Interval = 3*60*1000;
timer.Elapsed += startOtherTimerMethod;
timer.Start();

Edit: I should note that this is much the same as Peter Kelly's answer except that his solution is more elegant since it uses just one timer, no extra methods and takes advantage of the fact that the timer is changeable between runs. If you liked this answer, you'll love his. ;-)

Upvotes: 1

Peter Kelly
Peter Kelly

Reputation: 14391

One way of doing this would be to give the Timer Interval an initial value (e.g. 3 minutes). Then, in your Elapsed event handler, you could change the interval to your regular value which will be used from then on. 

 _timer.Interval = Utils.InitialCheckInterval;

 static void _timer_Elapsed(object sender, ElapsedEventArgs e)
 {
     if (_timer.Interval == Utils.InitialCheckInterval)
     {
         _timer.Interval = Utils.RegularCheckInterval;
     }

     DoTimeCheck();
 }

Upvotes: 4

Yahia
Yahia

Reputation: 70369

Use a System.Threading.Timer - the constructor takes a parameter for the delay of the first run and an interval for the subsequent runs.

Upvotes: 0

James Johnson
James Johnson

Reputation: 46047

Your UI resides on the same thread, so when you put the thread to sleep, it will cause your UI to hang as well. You need to run the timer on a different thread.

Upvotes: 1

Luis Valencia
Luis Valencia

Reputation: 33978

You should not use thread.sleep in this situation you should use the winforms control

BackgroundWorker which never locks the main UI. You can write your logic there.

example here: http://www.knowdotnet.com/articles/backgroundworker.html

Upvotes: 0

Kiril
Kiril

Reputation: 40345

It appears (although you've not shown that code) that you're calling Sleep(TimeToDelayFirstRunInMiliseconds); on the main/GUI thread, so that's what's causing your UI thread to hang. Instead, you should set your timer to be delayed by 3 minutes on the first run, then once it runs you change the timer again to run at the frequency you desire for all the subsequent runs.

Upvotes: 1

m.edmondson
m.edmondson

Reputation: 30862

Your UI needs a seperate thread, currently you are also sleeping the UI. Check this post.

Upvotes: 0

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