You may think of time as constantly, steadily ticking away, but in reality scientists occasionally must make adjustments to earth’s clocks in order to align them with solar time. They do this by periodically adding “leap seconds” — an extra second to the last minute on December 31. Unfortunately, setting the clock back by one second can cause major problems for applications that are constantly and quickly writing data to servers.
In order to deal with leap seconds, Google engineers came up with a solution they call the “Leap Smear.” Essentially, they lie to their servers about the correct time, adding milliseconds over the course of a day so that their internal clocks will already be showing the correct time after the leap second occurs.
