This weekend with daylight savings, we had a situation that when the system clock hit 3:00am from the jump, we had hundreds of processes fire off out of the crontab. Everything I'm reading says that if you schedule processes during this time and you're running the system in the local timezone, then you may have scripts not run at all (since you skip over the 2:00 hour). However, in this situation, we had several processes spawn 50+ times out of the cron.

Has anyone experienced why several processes would be executed so many times? Again, I've read that they may run twice, or not at all (depending on fall/spring), but 50+ times?

Each script that ran was scheduled at the top of the hour of 3:00, and not again for at least an hour. Here are a few:

0  3  * * *
0 0-6 * * *
  • 1
    Did you thought about setting up a virtual machine? With a VM you can check in advance if and how your crontab entries will get executed during the clock adjustment.
    – scai
    Commented Mar 10, 2014 at 15:10
  • Interesting, but not really a programming problem. Suggest you flag and ask moderator to move to linux.stackexchange.com. Good luck!
    – shellter
    Commented Mar 10, 2014 at 16:34
  • To keep my sanity (or what is left of it, anyways), I put all my servers in UTC. Been paged far too many times due to horrible things happening because some server clock leaped around and broke things.
    – thrig
    Commented Aug 29, 2015 at 17:54

1 Answer 1


It looks like this was a bug in the version of crond that we were running documented here: https://bugzilla.redhat.com/show_bug.cgi?id=436694

I was able to replicate in a VM upgrading to 1.4.4-12 fixed the issue. Thanks for all the replies!

  • That's nice to know, thanks for the information.
    – scai
    Commented Mar 11, 2014 at 7:25

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