Sam Varshavchik <[EMAIL PROTECTED]> wrote: > It's been brought to my attention that OpenBSD 3.2 can assign the same pid > to different processes in the same chronological second (that is, one > process terminates, and its pid is immediately assigned to a new process > that's created soon thereafter). > > Since filenames for messages in maildirs are generated based on the > combination of the pid, and the current time, in seconds, there is now a > race condition that will result in loss or corruption of mail. This breaks > Courier and Qmail. Example: process A delivers a message to a maildir just > before process B reads Maildir/new, and A's message is moved to Maildir/cur > a short time after it's been delivered, and A exits; meanwhile process C > starts, and delivers mail to the same maildir; its generated filename will > now be the same; so now you will have two messages with the same base > filename in the maildir). > > This is not theoretical. This been brought to my attention after someone > managed to succesfully deliver two messages with the same filename, on a > piddly Athlon (as part of a Courier "stress test"). Let's have a round of > applause for such a noteworthy accomplishment!
Ah, I was testing Courier on a OpenBSD 3.1 machine, and noticed a bit of odd behavior. This must be the cause of it! I had previously run the stress test for mail delivery. When delivering a large number of messages at once (like 5000) using that test script, I would see a few (like 1 to 3) messages somehow dropped. I never got any error messages from Courier, and nothing else seemed to be a problem. No stuck processes or anything. At first I thought it was an NFS problem (all Maildirs were NFS mounted), but setting up an account for local delivery didn't help. I've applied the patch to my copy of Courier 0.39.1 on that same OpenBSD 3.1 machine and re-run the perftest1 program. Now it seems to work fine, with no dropped messages. Kudos to Sam and whoever it was that made the connection to recycled PIDs. James Graves, CTO Delta Mobile Software http://www.deltamobile.com ------------------------------------------------------- This SF.NET email is sponsored by: FREE SSL Guide from Thawte are you planning your Web Server Security? Click here to get a FREE Thawte SSL guide and find the answers to all your SSL security issues. http://ads.sourceforge.net/cgi-bin/redirect.pl?thaw0026en _______________________________________________ courier-users mailing list [EMAIL PROTECTED] Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
