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Re: Suggestions on the use of lockfiles? [message #34009 is a reply to message #33919]

Mon, 10 February 2003 20:01

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

Jonathan Greenberg <greenberg@ucdavis.edu> writes:
> Robert:
>
> Thanks! That sounds fine, and is almost what I had come up with
> (incidentally, I finally found out the term for this is a "race condition",
> since I'm not a programmer it took some searching so I could find an
> official term for what was happening) -- here's the only possible issue that
> I was concerned about:
>
> If two computers openw,/APPEND and printf the same file, let's say their ID
> (computer #1 = 100 and #2 = 200), do we only have 2 possibilities in IDL:
... examples of two processes overwriting each other...

What you need to do is make an atomic operation. One way to do that
is write the data to a temporary file, then use rename or "mv" to
rename the temp file to the lockfile name. Since "mv" should be
atomic, there will be no race condition, and the file will be moved
complete. Then proceed from there.

Craig

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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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		Re: Suggestions on the use of lockfiles? By: Jonathan Greenberg on Sun, 09 February 2003 22:16
		Re: Suggestions on the use of lockfiles? By: rmoss4 on Sun, 09 February 2003 12:08
		Re: Suggestions on the use of lockfiles? By: Craig Markwardt on Mon, 10 February 2003 20:01

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