Meta Believes the Leap Second Has Outlived Its Usefulness

Better late than never

  • An artificial second, known as a leap second, to help keep clocks in sync with Earth’s rotation, has caused major internet outages in the past.
  • In a blog, Meta engineers made a case for discontinuing the practice while suggesting alternatives.
  • Experts welcomed the move but warned that the industry needs to agree on a replacement, or else they’ll further complicate the issue.
A clock breaking into flying pieces which lead to a metal chain.

summerphotos / Getty Images

Meta is fed up with a single artificially inserted second causing massive disruptions on the internet and has come up with a plan to do away with the practice. 

Known as a leap second, the extra tick was chalked up in 1972 as a means to keep clocks in sync with the Earth’s actual rotation. Computers have a hard time digesting the leap second and cause all sorts of issues trying to make sense of the anomaly, occasionally throwing the internet and other connected systems into disarray. Engineers at Meta have recently blogged about their intention to build momentum to scrap the leap second, arguing it causes more issues than it solves. 

"Time in computers underpins a shocking amount of critical infrastructure, and so precision is key," Patrick McFadin, Vice President of Developer Relations at DataStax, told Lifewire over email. "Daylight saving, leap years, and leap seconds all break the linearity of time."

Dance of Time

The need for the leap second arose because Earth’s rate of spin is somewhat irregular. Since 1982, there have been 27 leap seconds added to the world’s common clock, Coordinated Universal Time (UTC), in order to bring it in sync with solar time. 

In their post, Meta argued that every leap second is a major source of pain for people who manage hardware infrastructures.

"It's not so much the computers themselves that don't like leap seconds; rather, it's the software we write for them not being prepared for leaps," Jake Jervey, senior infrastructure engineer at Cobalt, explained to Lifewire in email. "Software engineers make two common but, thanks to leap seconds, incorrect assumptions: time can't go backward, and two events can't happen at the exact same time stamp."

It’s these two assumptions where introducing the artificial second can cause major bugs in systems for which timing and scheduling are concerns, pointed out Jervey.

Meta describes another possibility with the use of the leap second, which hasn’t occurred yet but could be equally disruptive. Since the Earth’s rotation pattern is dynamic, it’s very likely that it picks up speed causing the developers to account for a negative leap second.

"The impact of a negative leap second has never been tested on a large scale," asserted Meta in their post, adding, "it could have a devastating effect on the software relying on timers or schedulers."

All things considered, McFadin said the issue with the use of the leap second could be understood as a confrontation between scientists and engineers where the precision of science clashes with the practicality of engineering. 

Nobody will notice if we don’t keep up with leap seconds, but everyone will see if we get it wrong.

"Gaps in time or worse, time stamps before the current time can create a real existential crisis in computers just trying to follow instructions," said McFadin.

Move With the Times

In their post, Meta argued that while the leap second might have been an acceptable solution in 1972 when it made both the scientific community and the telecom industry happy, these days, the reliance on UTC is equally bad for both digital applications and scientists. 

"At Meta, we’re supporting an industry effort to stop future introductions of leap seconds and stay at a current level of 27," noted Meta in the post. "Introducing new leap seconds is a risky practice that does more harm than good, and we believe it is time to introduce new technologies to replace it."

McFadin added that engineers everywhere are having a real moment and coming around to admit that the cure is worse than the illness. 

"Making changes to foundation-level components like exact time seems like something we should be able to do," said McFadin. "As an industry, we’ve never been able to do it without creating havoc."

Someone working on a clock in a clock shop.

Peter Dazeley / Getty Images

The situation reminds Jervey of the infamous Y2K bug, and our experts welcomed Meta’s move asserting that it's about time this issue was tackled. However, like McFadin, he stressed the importance of coordination between all the stakeholders, or else writing software for date and time handling will become a lot more complex for developers.

"Most systems we’re talking about are human-readable data, such as a timeline on social media," explained McFadin. "Nobody will notice if we don’t keep up with leap seconds, but everyone will see if we get it wrong."

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