Elementary! MySQL did it, in the CPU, with the the leap second!

I awoke to an alert from a small Ubuntu 12.04 server I have on Linode: lots of CPU usage this morning,which is odd since I haven’t logged in for a while. Hmm. Looked at the CPU graph first, and the high usage was all since exactly midnight. Hmm again.

So, I groggily log in and start looking around, and immediately see that MySQL is using LOTS of CPU all by its lonesome. I immediately wondered if somehow a hacker got in or something (given the recently reported MySQL bug) so I went to look for some hints on investigating that. On a whim (remembering the odd timing of this) I searched Google for “mysqld went to 90% cpu at midnight”. Sure enough, it’s probably a bug.

Turns out, this weekend sports a rare “leap second“… and that triggers a kernel bug which in turn causes MySQL to start eating CPU like a bad gambler at a casino buffet.

I found the following suggestion (found here and here) worked well enough for me on its own (fingers crossed anyway):

sudo date -s "`date`"  # <-- Mind the backticks!

I ran that and the problem immediately disappeared. I didn’t need to reboot or restart mysqld (rebooting would also fix it apparently, but restarting mysqld would not).

Hopefully this bit of advice serves you as well!


  1. Well… thank you very much 🙂
    I was looking with no success if somebody hacked my server, when I stumbled on your post.
    It fixed mysqld usage.



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