Don't copy the old file to the new file, rename the old file over the new file. Then you don't need a lock and the only race condition is that a process might (depending on OS and how you do the rename) see no such file for a very short bit of time.

Update: The rename() function is atomic on many operating systems, by the way. And make sure each process doesn't open the file in a way that prevents it from being renamed/deleted/unlinked. For Unix, that isn't a problem. For Win32, unfortunately, I don't think I have a great solution at the moment -- but I'm close so let me know if you (or anyone) needs a fix for this.

        - tye (but my friends call me "Tye")

In reply to (tye)Re: Each process needs to read the newest version of the file by tye
in thread Each process needs to read the newest version of the file by Anonymous Monk

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