A customer of mine is experiencing a very strange problem: a scheduled task is running twice from time to time, with only a few seconds between execution.
The task is scheduled using the windows scheduler. It's a very basic task that connects to a local service using TCP/IP, authenticate, gives it a command and disconnect. It is nearly instantaneous (the longest part actually is the SSL handshake).
It triggers an issue in the server application which I will fix but my problem is that I simply cannot find any valid reason why the task is being run twice: nobody is ever connected interactively to that machine (it's an application server) and the server log shows that all these connections come from 127.0.0.1. Sending port and thread IDs both changes indicating in a very clear way that this is no some internal "ghosting" effect in the server application.
Unfortunately, task history wasn't enabled on that server so I don't have a run trace on that front. I have enabled it and, should the problem occur again, I will check it. I've verified, however, that nobody was connected to the machine around the time to issue occurred.
Can anyone explain this ?