History

Since 1972, the world's timekeeping authorities have added a leap second 27 times to the global clock known as the International Atomic Time (TAI). Instead of 23:59:59 changing to 00:00:00 at midnight, an extra 23:59:60 is tucked in. That causes a lot of indigestion for computers, which rely on a network of precise timekeeping servers to schedule events and to record the exact sequence of activities like adding data to a database.

What leap second in simple?

Leap seconds are adjustments that are periodically added to Coordinated Universal Time (UTC) in order to synchronize it with the Earth's rotational time, known as International Atomic Time (TAI). Leap seconds can be positive, meaning they add an extra second to UTC, or negative, meaning they remove a second from UTC.

The concern among big Giant companies?

Companies like Facebook, Google, and Microsoft are concerned that negative leap seconds can cause problems with their systems. Negative leap seconds can cause unexpected issues with software designed to work with UTC, as it may not handle the sudden removal of a second. This can cause systems to crash, display incorrect time stamps, or experience other errors.

In addition, negative leap seconds can cause issues for financial systems, as they may not properly account for the missing second, leading to incorrect transactions and other issues. This can cause significant problems, as financial systems rely on accurate time stamps to function properly.

Therefore, companies like Facebook, Google, and Microsoft have taken steps to mitigate the potential impact of negative leap seconds on their systems, such as using alternative time standards that do not include leap seconds or developing custom solutions to deal with them.

Why Meta, Google, and Microsoft stopped using leap second? Meta explains, "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." Therefore, we should simply "stop the future introduction of leap seconds."

Here is a summary from Meta Blog

So far, only positive leap seconds have been added. In the early days, this was done by simply adding an extra second, resulting in an unusual timestamp:

23:59:59 -> 23:59:60 -> 00:00:00

With the Earth’s rotation pattern changing, it’s very likely that we will get a negative leap second at some point in the future. The timestamp will then look like this:

23:59:58 -> 00:00:00

The impact of a negative leap second has never been tested on a large scale; it could have a devastating effect on the software relying on timers or schedulers. In any case, every leap second is a major source of pain for people who manage hardware infrastructures.

Will 2022 have a leap second?

No, the International Earth Rotation and Reference Systems Service (IERS) decided not to add a leap second in 2022. The IERS regularly monitors the difference between UTC and TAI and decides whether or not to add a leap second. The most recent leap second was added on June 30, 2015, and there have been no leap seconds added since then.

Summary

On November 18, 2022, at the 27th General Conference on Weights and Measures, it was decided to abandon the leap second by or before 2035. The implementation of the change is expected to take place by or before 2035.

Thanks for reading!