Sheeri K. Cabral at the Mozilla Foundation wrote about an issue with the June 30th 2012 leap second affecting at least MySQL, Java and Minecraft servers. It now appears that the underlying cause is a Linux kernel bug, as noted by John Stultz (IBM) on the Linux Kernel mailing list, and the team Sheeri is part of deserves due credit for doing awesome pattern recognition and being the first to bring it to public attention, enabling people to quickly correlate their own experience with that of others and finding a practical solution as well as helping figure out the cause.

Sheeri’s original post MySQL and the Leap Second, High CPU and the Fix describes how MySQL servers would suddenly exhibit high CPU usage during a period of low load. …