Windows 10 and Windows Server 2019 To Support True UTC-Compliant Leap Second (thurrott.com)

Mehedi Hassan, writing for Thurrott: Microsoft is bringing support for leap seconds -- yes, that one extra second -- to Windows, starting with Windows 10 Redstone 5 and Windows Server 2019. With the upcoming updates for Windows 10, Microsoft's operating system now deals with leap seconds in a way that is incredibly accurate, UTC-compliant, and traceable. Leap seconds typically occur every 18 months, resulting in one extra second. The extra leap second occurs to adjust with the earth's slowed down rotation, and an extra second is added to UTC in order to keep it in-sync with mean solar time. To deal with the extra second more appropriately, Windows 10 will now display that extra second, instead of directly jumping to the next one. H/T Perfycat who adds: The new move makes Windows Server the first OS to have full support of the rare but valid timestamp of: 23:59:60. Linus Torvalds has long maintained that users needs to chill out about leap seconds. Further reading: Microsoft's blog post 1, and blog post 2.

Comments

BIOS as GMT Time

[Drakster]

Can this help with setting the BIOS as UTC time, much like all other operating systems? I know you could enable it in the past using the registry, however from what I remember, this caused further problems.

Y2K reapeat?

[kiviQr]

am I the only one that expects cities glowing in blue (BSOD) the first time system hits 23:59:60?

Programming falsehoods concerning time

[marquis111]

Puts me in mind of a very informative blog post I read years ago about popular programming falsehoods about time.

https://infiniteundo.com/post/25326999628/falsehoods-programmers-believe-about-time
https://infiniteundo.com/post/25509354022/more-falsehoods-programmers-believe-about-time

Unix systems had it first

[guruevi]

Leap second support has been in Linux and other Unix systems forever. The problem is the many standards on how to implement leap seconds. They are generally a representational problem, not a counting problem. It’s similar to time zones, they are arbitrarily defined and thus not very useful for true mathematical implementation. Microsoft has picked one of the dozen or so standards on how to represent leap seconds. The fact is that you should pick whatever method is suitable and useful for interoperation with the rest of stuff you have.

Re:Unix systems had it first

[thegarbz]

After all, it's why we have things like libraries

I know. Libraries are just delivered by magic unicorns. /sarcasm. My point was not application programmers, but rather programmers in general. Time is hard. Even when you think you can offload it to a library time is still hard. Even if we have a perfect time keeping library you still end up dealing with application requirements that will require time to be handled in a special way, e.g. a calendar or an app that communicates between different countries.

Programmers need to remain vigilant even when they do use libraries. Time is hard.

Windows Server 2019 Features

[DickBreath]

The only feature I need in Windows Server 2019 is to be able to set my hostname to all emoji characters. Thank you.

read the MS Dev document

[at10u8]

The MS blog entry points at a Dev document about how it works, and that says this:
Known issues: Some frameworks are known to calculate time incorrectly after a leap second occurs. For example, the .NET Framework uses its own internal logic to determine what time it is. Its logic does not account for leap seconds. So after a leap second is introduced to the Operating System the output of "System.DateTime.Now.ToString()" will be ahead by one second of the local system time. (We are working with the .NET framework team on this.)
Combine that with the many many steps on how to configure Win10 makes this sound like a really interesting new feature.