Windows Service sends mailing multiple times after restart

Peter

Hi all,

I have a problem with a service that sends mailings to customers. Basically, what the mailing does is check a database table for scheduled mailings to send. When it finds one, it gets the addresses from another db table and loops through them to send an email to every address.

This works fine except in the following two situations.
1. After a restart of the service, if there are mailings scheduled, the first mailing to be sent is sent twice. Later mailings are ok.
2. After a reboot of the server and a restart of the service it is the same except that the first mailing gets sent multiple times, up to 19 times!! Later mailings are again ok.

It doesn't seem to be a problem in the code (c#) because it only happens the first time after a restart (or is that short-sighted?). It only happens after a restart when there is already a mailing waiting to be sent. When the service is started with no mailings waiting and I then add a new mailing, everything works fine.

Any ideas? Any help would be greatly appreciated.

Peter

5 Replies

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Peter15y ago
Thank you Sam for your answer. I removed the Thread.Sleep and problem number 1 is solved.
I just found out what the other problem was. I set my timer to 100 ms and on elapse started to send mailings. The routine that sends the mailing sets a flag to indicate that a mailing is running and no action should be taken until the mailing is finished. However, this flag was not set until more than 8 seconds after the first elapse. So every time the timer elapsed a new run was initiated right until the flag did get set. It only takes so much time for the flag to be set during startup after a reboot.
I simply set the timer to one minute and the problem went away.

Again thanks for your help.

Peter
Sam Hobbs15y ago
Many people like to use sleep because it is easy. There often are problems with it however. It is probably not the problem here but I would not use sleep. If it was the problem, then it is probably because it does not allow the operating system the opportunity to do stuff that it needs to do for your thread. If it was me I would use a timer instead. As I say, I don't think it is the problem here but I wanted to mention the possibility anyway.
Sam Hobbs15y ago
I assume that the problem is related to how the service determines what has been sent. It seems possible to me that there might be something that your program does that the operating system does not have the opportunity to complete. If so then you will not see the problem by looking at your source code. The problem of it sending the same mailing more than a second time is certainly strange.
Peter15y ago
The loop that sends the e-mails lets the thread sleep for half a second.
Can you expand on your answer?
Rahul M15y ago
Have you implemented threading in your code?