timer - Code for executing method every day at specific time C# (Windows Service) failed

Question

I had this code to execute method of windows service every day at 5am:

EDIT:

MyService ws = new MyService ();

protected override void OnStart(string[] args)
{
    if (serviceHost != null)
    {
        serviceHost.Close();
    }

    serviceHost = new ServiceHost(typeof(MyService));

    serviceHost.Open();
    double TimeOfExecution = 5;

    DateTime now = DateTime.Now;
    DateTime today5am = now.Date.AddHours(TimeOfExecution);
    DateTime next5am = now <= today5am ? today5am : today5am.AddDays(1);

    System.Threading.TimerCallback callback = new System.Threading.TimerCallback(ws.MethodToExecute());

    var timer1 = new System.Threading.Timer(callback, null, next5am - DateTime.Now, TimeSpan.FromHours(24));

 }

I expected the Service to execute at next 5 o'clock, and every 24 hours after that.

Method MethodToExecute() did get executed at 5 o'clock (or some other specified time) that day, but next day it failed to execute. Also, it seems that it does not matter if I executed it or not for the first time, but it seems like service goes to sleep after some time and doesn't execute, so if 5 o'clock arrives not at current day, but next day, it will fail to execute.

Does anyone have an idea what could be wrong?

Answer 1

GC will collect your timer since you don't have any references to it after OnStart method.

You're just having it as a local variable. I hope you know local variables are eligible for garbage collection once JIT says that they are no longer used in code.

Fix: Just store the timer in a instance variabe, you're done.

private System.Threading.Timer my5AmTimer = null;

protected override void OnStart(string[] args)
{
    //All other code..

   this.my5AmTimer = new System.Threading.Timer(callback, null, next5am - DateTime.Now, TimeSpan.FromHours(24));
}