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10.4: One solution to a launchd-cron CPU usage issue
Authored by: shoelzer on Sep 15, '05 03:10:45PM
I believe I know what happened to the postee.

The QueueDirectories key in the plist tells launchd to monitor that folder and run cron whenever something is there. (Not just when something is created or updated, but if something exists.) So cron starts, looks in /var/cron/tabs and sees the .DS_Store file. It treats that file as a crontab but can't make sense of it and crashes. launchd does what it should and restarts cron.

The cycle repeats and eats your CPU.

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10.4: One solution to a launchd-cron CPU usage issue
Authored by: Michael Levin on Nov 01, '05 01:23:05PM

Aha!! This might be what's happening to us. I'm a biologist with a fading memory of Unix administration from 10 years ago... I just set up a Tiger Xserve for our lab and everything was fine for a while and then the CPUs started maxing out at 100% due to cron activity! I suspect I may have the same problem as reported here. How in general can I avoid this in the future? I won't be using Finder to dig around in those folders, but if something does show up in that directory which causes cron to crash and be restarted, I'll have a problem again. How do people manage this issue? Is it really necessary for "cron to watch the /var/cron/tabs directory for new crontabs"? Can I turn that feature off, or is there a better/more elegant way to make sure this never happens? What should be in that directory, anyway? Currently, I see:

[mail:~] mlevin% ls -al /var/cron/tabs
total 48
drwxr-xr-x 8 root wheel 272 Nov 1 10:57 .
drwxr-xr-x 3 root wheel 102 Mar 20 2005 ..
-rw------- 1 root wheel 278 Oct 18 10:12 cyrusimap
-rw------- 1 root wheel 689 Nov 1 10:57 diradmin
-rw------- 1 root wheel 1490 Nov 1 10:57 mailman
-rw------- 1 root wheel 278 Nov 1 10:57 root
-rw------- 1 root wheel 268 Oct 10 03:14 test
-rw-r--r-- 1 root wheel 275 Nov 1 10:21 tmp.995

any help would be greatly appreciated. I need to know how to keep that directory clean! Thanks in advance.

Mike



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