check if the same function is already running, then exit!

[Suresh Raja <suresh.rajaabc@xxxxxxxxx>]

Before running a running a function, i would check only 1 instance is running.  If alreaady a function is running, the existing function should exist with the msg that already a function with same is running.

If somebody has already used such a faeture, can u please share or 

Can you tell me the table and column from which I could this info.

Thanks,