It’s been 10 years since we had the last leap second and it looks like we will get the first negative one soonish. Are systems ready for that?
Ask HN: Are systems ready for the first negative leap second?
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Re: Ask HN: Are systems ready for the first negative leap second?
#2NTP.
By any other standard, most manually set clocks are up to a full minute off all the time.
Re: Ask HN: Are systems ready for the first negative leap second?
#3Systems are absolutely not ready. Leap seconds are a bad idea and negative leap seconds are worse. Just don't do it and let the drift cancel out.
Re: Ask HN: Are systems ready for the first negative leap second?
#4Google's proposal is a smear. [1] Most time servers do not use smear. No idea what behavior it may introduce in places where sub-second time is important. Curious if all these bugs [2] were fixed specifically to deal with going backwards.
Re: Ask HN: Are systems ready for the first negative leap second?
#5[flagged]
Re: Ask HN: Are systems ready for the first negative leap second?
#6NTP. By any other standard, most manually set clocks are up to a full minute off all the time.
Yeah, but we're thinking of systems where nanoseconds matter.
MiFID 2 alone forces sub-μs precision. Million times less than the leap 1 second.
NTP minute away is good for displaying date on the workstation, not for many of the devices that are critical to the modern world.
Re: Ask HN: Are systems ready for the first negative leap second?
#7NTP. By any other standard, most manually set clocks are up to a full minute off all the time.
Yeah, but we're thinking of systems where nanoseconds matter. MiFID 2 alone forces sub-μs precision. Million times less than the leap 1 second. NTP minute away is good for displaying date on the workstation, not for many of the devices that are critical to the modern world.
dont most systems that rely on sharp timing simply manage it themselves.
Re: Ask HN: Are systems ready for the first negative leap second?
#8Earlier quoted context omitted.
Yeah, but we're thinking of systems where nanoseconds matter. MiFID 2 alone forces sub-μs precision. Million times less than the leap 1 second. NTP minute away is good for displaying date on the workstation, not for many of the devices that are critical to the modern world.
dont most systems that rely on sharp timing simply manage it themselves.
Yesno.
Sure they have their own time servers fed from the GPS, but they need to be _accurate_ in relation to the world.
But timestamps used by companies forced to use very accurate timing must be synchronised to UTC.
Re: Ask HN: Are systems ready for the first negative leap second?
#9If we have positive and negative leap seconds, why are we doing anything at all? 1 second forward, just to go 1 second back 10 years later…
Re: Ask HN: Are systems ready for the first negative leap second?
#10Google's proposal is a smear. [1] Most time servers do not use smear. No idea what behavior it may introduce in places where sub-second time is important. Curious if all these bugs [2] were fixed specifically to deal with going backwards . [1] - https://developers.google.com/time/smear [2] - https://rivassec.com/leap-second-chaos-2012.html
The brilliant thing about the smear is that it distributes the new second across each second of the day, so that each second differed by 1/86400 seconds, well within the margin of error for NTP.
As far as the computers were concerned, nothing was different.