1 July 2012

This morning Gregor Samsa woke up... oh, pardon! This morning I woke up and found myself puzzled, because my home server was eating up all of my 4 cores CPU cycles. Especially mysqld was high on CPU load. 100% CPU load for the mysql-server instance and 100% CPU load for akonadiservers own mysqld instance. Restarting KDE and mysql-server didn't help on my Debian unstable machine. Next step was upgrading the system. Sometimes this helps indeed, but not today. Looking at bugs.debian.org for mysql-server didn't reveal any help as well. So my next logical step was to ask on #debian-devel in IRC. And my question was very quick answered:

11:28 < ij> since tonight I've got two mysqld processes running at 100% CPU, one spawned by akonadi and
the other is the mysqld from mysql-server (unstable that is). is this an already known issue?
haven't found anything on b.d.o for mysql-server, though
11:29 < mrvn> ij: topic
11:29 < mrvn> you need to set the time
11:30 < ij> waaaaah!
11:30 < mrvn> ij: indeed.

The topic was at that time:

100% CPU? Reset leap second http://xrl.us/bnde4w

So, it was caused by the leap second. Although you might suspect mysql doing some nasty things (which, IMHO, is always a good guess ;)), the issue is this time within the Linux kernel itself, as a commit on git.kernel.org clearifies. To fix this issue you need to set the time manually using the following command or just reboot:

date -s " date "

So far I found these applications being hit by this kernel bug:

• mysql-server
• akonadi (as it uses own mysql instances)
• Firefox
• Openfire Jabber server (because it's using Java, which seems to trigger the problem as mysql does)
• Virtualbox' VBoxSVC process
• puppetmaster from package puppet, reported by Michael
• mythfrontend, reported by pos on #debian-devel
• Jetty, Hudson, Puppet agent and master, reported by Christian
• milter-greylist, reported by E. Recio
• dovecot, reported by Diogo Resende
• Google Chrome, reported by Erik B. Andersen
• if you find more apps, please comment and I'll include them here...

So, hope this helps and many thanks to mrvn and infinity on #debian-devel for the help!