michael.groh (3/31/2009)

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It always concerns me when I see an endless loop used as a timing device. It'd seem that having a number of packages running on a server, each using an endless loop as a file watcher, might be detrimental to performance.

It's very easy to add a "Sleep" statement in the body of the loop to put the thread to sleep for a few seconds or minutes:

System.Threading.Thread.Sleep(milliseconds)

I've done the file watcher thing by putting the thread to sleep for 60000 milliseconds (one minute), and counting how many minutes have transpired before failing the task:

Dim i As int

While True

If System.IO.File.Exists(Dts.Variables("FlatFileConnection").Value.ToString)Then

Exit While

Else

System.Threading.Thread.Sleep(60000)

i += 1

'Exit after 240 minutes (4 hours):

If i > 240 Then

Exit While

End If

End If

End While

This is much simpler and more efficient code than using a DateTime variable and comparing it's value to Now(). The way the code in this article is written, Now() is called millions and millions of times in the body of the loop, while in the revised loop, the comparison is performed only once a minute, and, at most, 240 times. The revised loop achieves the same objective while requiring a lot fewer CPU cycles.