Using System.Timers.Timer in asp.net

Question

I use the following code in a asp.net website.

On application init i call InitializeTimer() once.

The goal of the code was to run DoWork() once every hour (1 time per hour) .

I also wanted the code to execute on different time every loop so i added the random part.

The result i got was werid , i can not find a explaination why is happens.

The code executed the function after 2hrs , then again after 2hrs , then after 3hrs , then after 2hrs , and 2hrs again.****

Can anybody explain the reason?

using System.Timers;
....
private static random = new Random();
....
public static void InitializeTimer()
{
    tTimer = new Timer();
    tTimer.AutoReset = true;
    tTimer.Interval = TimeSpan.FromHours(1.0).TotalMilliseconds;
    tTimer.Elapsed += new ElapsedEventHandler(ClassName1.tMailer_Elapsed);
    tTimer.Start();
}

private static void tTimer_Elapsed(object sender, ElapsedEventArgs e)
{
    tTimer.Interval += random.Next(-5, 5);

    DoWork();
}

Update:

Please don't post "use windows service" , or "scheduled task". My question is for the following code I'm not looking for better alternatives. Also , during this test (10hrs) , website was with high traffic , iis pool did not restart!
Based on the following MSDN: (http://msdn.microsoft.com/en-us/library/system.timers.timer.interval.aspx)

If the interval is set after the Timer has started, the count is reset. For example, if you set the interval to 5 seconds and then set the Enabled property to true, the count starts at the time Enabled is set. If you reset the interval to 10 seconds when count is 3 seconds, the Elapsed event is raised for the first time 13 seconds after Enabled was set to true.

Is it possible that re-setting the interval in the elapsed function is the cause of the problem?

Meaning that when tTimer_Elapsed function is called the count is 1hr(min a few millisecond) and my code "tTimer.Interval += random.Next(-5, 5);" is adding another full hour to the Interval?

If you take out the random part, does the code work as expected? — mpeterson
– mpeterson, Commented Feb 13, 2010 at 1:35
i dont know , the code is running on producation server , i cant change it now (a wont be able for a few days) , thats why i asked the question to find a explaination. — RuSh
– RuSh, Commented Feb 13, 2010 at 10:39
So does that mean it performs as expected when testing locally? — mpeterson
– mpeterson, Commented Feb 13, 2010 at 16:45
RuSh, So in other words, you're asking us to help you do it the wrong way despite the fact that Microsoft advised against using System.Timers in ASP.NET? (see learn.microsoft.com/en-us/dotnet/api/…) — RashadRivera
– RashadRivera, Commented Dec 29, 2021 at 14:11

Samuel Neff · Accepted Answer · 2010-02-12 22:31:18Z

7

ASP.NET applications will get shut down when not in use. If someone hits your site, and then no more hits, it can get shut down. Your timer won't fire.

For this type of maintenance work you want to use a windows scheduled task or windows service.

answered Feb 12, 2010 at 22:31

Samuel Neff

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3 Comments

RuSh Over a year ago

thx for the input. the website or iis pool were NOT restarted during the test. i belive something is wrong with my code.

Jader Dias Over a year ago

@sharru IIS recycles your application without user intervention.

RuSh Over a year ago

i aware of that , i log those events , no restart happened.

Community · Accepted Answer · 2021-01-18 12:38:11Z

3

Check this out... Jeff Atwood actually discussed something similar. I guess it worked, but according to Jeff the site outgrew this method so they went to a dedicated task.

edited Jan 18, 2021 at 12:38

CommunityBot

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answered Feb 13, 2010 at 1:32

mpeterson

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1 Comment

Ian Kemp - SO dead by AI greed Over a year ago

Yeah, probably the only reason that worked is because SO never idles out in IIS...

Ian Kemp - SO dead by AI greed · Accepted Answer · 2020-06-19 10:59:30Z

1

Since .net 4.5.2, there is a class called HostingEnvironment, it can do what you're asking, here is how to use: https://blog.mariusschulz.com/2014/05/07/scheduling-background-jobs-from-an-asp-net-application-in-net-4-5-2

The HostingEnvironment.QueueBackgroundWorkItem method lets you schedule small background work items. ASP.NET tracks these items and prevents IIS from abruptly terminating the worker process until all background work items have completed.

edited Jun 19, 2020 at 10:59

Ian Kemp - SO dead by AI greed

1

answered Jun 4, 2015 at 0:04

Alexandre

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1 Comment

Ian Kemp - SO dead by AI greed Over a year ago

This doesn't help the OP's issue, which is that the timer is not getting fired at the correct interval due to IIS idling out the app pool.

Steve · Accepted Answer · 2010-02-12 23:50:34Z

0

I second Sams suggestion of using windows scheduled task to hit a page every hour. I tried and tried to get mine to work and it sort of worked. I went to a scheduled task and it has never failed.

answered Feb 12, 2010 at 23:50

Steve

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