On the final minute of June 30, 2012, the number of seconds was 61 seconds long. The extra “leap second” was added to the clock to ensure official time clocks were accurately synchronized to the Earth’s rotation. This temporarily knocked down websites like Reddit, Gawker, and Foursuqare since neither Linux nor Java’s base application platform were prepared for the change.
Last year, Google detailed how they deal with leap seconds. Google uses a technique called “leap smear” where they gradually add milliseconds to their system clocks prior to the leap second arrival.
?This meant that when it became time to add an extra second at midnight, our clocks had already taken this into account, by skewing the time over the course of the day,? said Google. ?All of our servers were then able to continue as normal with the new year, blissfully unaware that a leap second had just occurred.?