Yes, I was using the lockfile from the procmail package. But I agree flock should work just as well. I saw both were available and arbitrarily picked lockfile for my testing.
Thanks for your work. -- Steve > Date: Fri, 10 Jul 2009 20:14:13 +0000 > From: dustin.kirkl...@gmail.com > To: steve30...@hotmail.com > Subject: [Bug 394556] Re: multiple running instances of update-motd cause > errors > > Nevermind, I found flock(1). It's working like a champ ;-) > > :-Dustin > > ** Changed in: update-motd (Ubuntu) > Status: Triaged => In Progress > > -- > multiple running instances of update-motd cause errors > https://bugs.launchpad.net/bugs/394556 > You received this bug notification because you are a direct subscriber > of the bug. > > Status in “update-motd” package in Ubuntu: In Progress > > Bug description: > Binary package hint: update-motd > > Description: Ubuntu 9.04 > Release: 9.04 > update-motd: > Installed: 1.11.1 > > When update-motd is executed out of /etc/cron.d, the instances are all set to > run at the same minute (if they run at all). This means that up to five > instances of update-motd can be started simultaneously. This causes two > problems-- > > 1. The method used to lock out simultaneous executions is not very robust. > The $NEW file, which is used as a synchronization lock, is tested early in > the script, but not created until later. This leaves a window open for > multiple scripts to get started, and then collide with each other, ultimately > messing up the resulting message of the day. At least on my machine, this > error happens about half the time on each hour. The code to "nice" the > process seems to be the part that opens the window the widest. Using > lockfile to create a semaphore for synchronization corrects this flaw. I've > created a modified version of update-motd and included it as an attachment. > > 2. By design, only one instance of update-motd can run at a time, and others > just exit. However, this means that some of the work scheduled for the same > minute doesn't get done (assuming the synchronization works correctly). But > this isn't really what you want--if both the 10-minute and the hourly script > are scheduled on the hour, you want both to execute serially. I can see two > possible solutions to this: > a) Alter the lockfile code in the attachment to allow retries. Changing -r0 > to -r5 in the attached code would allow all the instances that could possibly > be scheduled to take their turns to run. The downside of this solution is > that if update-motd is run manually, it could take up to 40 seconds to fail, > when the lock is in place. Even the 8 second delay for a single retry is > likely to be confusing to the user. > b) Alter the update-motd crontab entry in /etc/cron.d so that the instances > of update-motd don't coincide. For example, one job on the 10-minute > boundaries, one 1 minute after the hour, one 2 minutes after midnight each > day, one 3 minutes after midnight each week, one 4 minutes after midnight > each month. This change would also reduce the likelihood of multiple running > instances to the point that the current method of synchronization with the > $NEW file would rarely cause a problem. _________________________________________________________________ Hotmail® has ever-growing storage! Don’t worry about storage limits. http://windowslive.com/Tutorial/Hotmail/Storage?ocid=TXT_TAGLM_WL_HM_Tutorial_Storage_062009 -- multiple running instances of update-motd cause errors https://bugs.launchpad.net/bugs/394556 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
