Meta is putting its considerable weight behind the tech industry’s push to do away with the leap second. In a post on the company’s engineering blog, Meta production engineer Oleg Obleukhov and research talked scientist Ahmad Byagowi about how a leap second can wreak havoc on a network, along with the solution Meta implements to prevent outages and any issues it could cause.
The leap second was introduced back in 1972 as a way to adjust Coordinated Universal Time (UTC) and make up for the difference between the International Atomic Time (TAI), which is measured by atomic clocks, and imprecise observed solar time (UT1). They sometimes don’t match due to irregularities and slowdown in the Earth’s rotation caused by various climate-induced and geological events, such as the melting and refreezing of ice caps on the tallest mountains.
As Obleukhov and Byagowi note, the offset a leap second creates can cause issues all over the industry. In 2012, for instance, it took Reddit out for 40 minutes when the time change confused its servers and locked up its CPUs. A time leap added in 2017 also affected Cloudflare’s DNS service.
To prevent unwanted outages, Meta and other tech companies, such as Google and Amazon, use a technique called “smearing.” These companies “smear” a leap second by slowing down or speeding up the clock throughout a number of hours. Meta smears a leap second throughout 17 hours, while Google uses a 24-hour smear technique that lasts from noon to noon and encourages everyone to follow suit. That way, a leap second doesn’t create any weird time stamps that could throw networks off.
But Meta isn’t advocating for the adoption of its smearing technique — its new post’s purpose is to lend its voice to the movement that’s calling for the leap second’s retirement. The body responsible for deciding whether to adjust UTC, the International Earth Rotation and Reference Systems Service, has added 27 leap seconds since 1972. Meta believes that’s enough adjustment for the next millennium.
The company’s post comes over a year before the fate of the leap second is decided. Back in 2015, the International Telecommunications Union discussed the leap second at its World Radiocommunication Conference and came to the conclusion that further studies are needed to figure out the impact of dumping it. The union is expected to examine the studies’ results and to consider the proposal to retire the leap second at its next conference in 2023.
Meta said in its post:
“Leap second events have caused issues across the industry and continue to present many risks. As an industry, we bump into problems whenever a leap second is introduced. And because it’s such a rare event, it devastates the community every time it happens. With a growing demand for clock precision across all industries, the leap second is now causing more damage than good, resulting in disturbances and outages.”
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