[In a message on Thu, 11 Jul 2002 14:29:20 EDT, the pithy ruminations of "Michael Richardson" were:] > > Aside from trashing sequences (which I've experienced on occasion, no idea >why) > I've run into situations where I wind up doing an "inc" from two difference >sources into the same folder. Usually due to impatience on my part. > > The result was a mess of two processes using the same message numbers! > My impression is that inc doesn't do any locking on message numbers, but I >could be wrong.
I think anytime that there is a possibility of multiple processes writing to the same file, locking should be "enableable". Even if it's a command line switch (everyone likes to say "use procmail", but this is essentially what procmail does: locks file and folders by default, and you can disable or use a different file for locking if you choose). Over the years, we've had a LOT of email being trashed because of lock problems. We end up doing arcane workarounds to "fix" it. You can have timeout's on lockfiles, and "fail". You can have command line/compile time options to disable/change locking. But the sequence file and the next message should be locked when written. Oh, and the mail drop should be locked when it's being inc'ed. Using "locking" in the shell is only slightly better than no locking at all. . . Sean