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Leap second 2017 status
- baq 10y ago34 (or is it 35 now?) years since the first leap second, software still broken.
- AstroJetson 10y agoYea, but next time is about 2020 so there is time to fix it.
- jsjohnst 10y agoSay what? Leap seconds have been added 27 times in the past 45 years. What would lead you to believe the earth's rotation will stop slowing down over the next 33 years?
- AstroJetson 10y agoSorry, typo, was going for 2020
- SEMW 10y agoOK, so what makes you think the next one won't be till 2020? Leap seconds aren't like leap years, they're unpredictable, since the Earth's rotation varies in response to geological events etc. The IERS announces them six months in advance.
- jsjohnst 10y agoAdmittedly they've slowed down a lot since 2000 (happened at least 7x a decade in 80s and 90s), but I agree, saying 2020 further shows the poster doesn't understand how leap seconds work.
- AstroJetson 10y agoYikes!! I did a quick look at the periods between 1980 an now and guesstimated that it would be 35 months to the next leap second (2020). As a Ham radio person I get sun spots and solar winds which will make a difference on the rotation. But as an R programmer I went back and ran the numbers and it's looking like 2020. Happy to see that my Mark 1 Eyeball estimate was close. But I'm happy to see what your numbers are. With the advent of the Raspberry Pi support for time and the cheap GPS units, I run my time locally. See https://blog.ntpsec.org/ https://blog.ntpsec.org/ for details. And yes, I cleared the second change, but I in full disclosure it wasn't until 9 AM before I checked.
- jsjohnst 10y agoStatistically modeling them using the prior dates of leap seconds alone isn't a good method (if that's what you did, not claiming that it is). Knowledge of the past leap seconds doesn't really tell you anything about when future ones will be. A better way would be to model the difference between UTC and UT1 and model the rate of change there. Probably the best would be to model the earth's rotation rate and factor in the likelihood of the events that cause variances. One major source of those events is earthquakes.
- 21 10y agoWow, such amateur hour. I always thought that ntppool is run by competent people, and that each server has at least a GPS time source. They don't even seem to have a monitoring solution which can track what time each server is advertising. I would switch to time.nist.gov if they had any servers in Europe. Any other good NTP EU source?
- LeoPanthera 10y ago> They don't even seem to have a monitoring solution which can track what time each server is advertising. Yes they do. http://www.pool.ntp.org/scores/ http://www.pool.ntp.org/scores/ In fact the page linked to even specifically mentions removing bad servers from the pool in real time. > I would switch to time.nist.gov if they had any servers in Europe. You talk about "amateur hour" but are seemingly unaware that unless you are running an NTP server for a significant number of users yourself, you should not be using time.nist.gov. Given that you're apparently currently using the pool, I'm guessing you're not.
- 21 10y agoI was talking about this kind of monitoring: http://www.satsignal.eu/mrtg/pixie_ntp.html http://www.satsignal.eu/mrtg/pixie_ntp.html I never said that I'm a time expert. Regarding time.nist.gov, it's still there in the list of Windows 10 NTP servers that a user can select, albeit, by default it will only be polled once per week.
- toast0 10y agoIt's a free service, with volunteers providing the servers. There is monitoring, but as far as I'm aware, common ntpds don't relookup the configured servers while running, so you're going to be stuck to servers that tested good when your server started. The downside of nist.gov servers is that they're sometimes very overloaded (and the one hosted in Washington state tends to have network path asymmetry, resulting in a large time offset reported). There are some lists of public servers linked from this page: http://support.ntp.org/bin/view/Servers/WebHome http://support.ntp.org/bin/view/Servers/WebHome
- labster 10y agoThe astronomers responsible for leap seconds will be the first against the wall when the revolution comes. Down with UTC, viva la TAI!
- paulddraper 10y ago> astronomers responsible for leap seconds Why stop at them? I'd take on that inconsiderate Sol next.
- labster 10y agoAh, a geocentrist. Welcome to HN, and enjoy the EM-drive threads!
- kbaker 10y agoWow, did not know openntpd just ignores the leap second altogether. http://undeadly.org/cgi?action=article&sid=20150628132834 http://undeadly.org/cgi?action=article&sid=20150628132834
- benjibobs 10y agoThe end of the reply from naddy@ is pretty funny: "Any hate mail about leap seconds should be directed to (1) the people who insist that Earth's celestial wobbling around must have primacy for time keeping and (2) the people at POSIX who specified that time_t must not include leap seconds, which means we can't just let the time zone database handle this."
- NelsonMinar 10y agoYeah that surprised me too. It's not a crazy solution for a client machine, but no server running that should be providing time for others.
- m-p-3 10y agoAnyone running openntpd should be kicked out of the pool at this point.
- alpb 10y agoSome resources on how Google handles the leap seconds in their datacenters, where this is no longer a problem: - https://developers.google.com/time/ https://developers.google.com/time/ - http://www.businessinsider.com/google-compute-engine-leap-smear-deals-with-61-second-minutes-2015-6 http://www.businessinsider.com/google-compute-engine-leap-sm... - https://cloudplatform.googleblog.com/2015/05/Got-a-second-A-leap-second-that-is-Be-ready-for-June-30th.html https://cloudplatform.googleblog.com/2015/05/Got-a-second-A-...
- LeoPanthera 10y ago"Leap smearing" is a clever solution when dealing with software that cannot tell time properly, but it does mean that your clocks will be up to half a second out, on a day with a leap second. Useful perhaps if you run a datacenter, but a poor solution if you actually care about accurate timekeeping.
- tedunangst 10y agoA large part of the problem is people who think they care, but really don't.
- FLUX-YOU 10y ago"fleet of atomic clocks" is definitely a cool phrase.
- LeoPanthera 10y agoThe number of servers in the pool is slowly falling. If you can spare a server, why not join it? http://www.pool.ntp.org/zone/@ http://www.pool.ntp.org/zone/@
- LeoPanthera 10y agoI'm not a developer, but it seems to me that the proposal to eliminate leap seconds smacks of laziness. Keeping UTC within a second of UT1 has important real-world uses, including navigation and astronomy. The only problems it has created are software ones, and redefining how we measure time to cope with bad code seems like a ridiculous overreaction.
- CJefferson 10y agoI agree, we should design the best time system for the majority of people. None of this seems hard for any half decent bunch of programmers to deal with easily.
- deleted 10y ago[deleted]
- perlgeek 10y ago> Keeping UTC within a second of UT1 has important real-world uses, including navigation and astronomy. Really? I thought for both of those, you'd want to add some corrections anyway, like for astronomy, your longitude, because usually you aren't in the middle of your time zone anyway. And if you need to add corrections anyway, why not quit adding leap seconds and handle them in those corrections?
- LeoPanthera 10y agoYou are not wrong, but in the real world, getting hold of an accurate representation of UT1 is very difficult, but knowing accurately UTC is very easy, and so in practice this is what is used for everyday civil purposes.
- vilhelm_s 10y agoIt it really so difficult? The difference between UTC and UT1 is broadcast by the different radio services, and you can also get it online (ftp://hpiers.obspm.fr/iers/bul/buld/bulletind.dat). Also, apparently NIST makes UT1 available over NTP so you can just point your computer to it (https://www.nist.gov/pml/time-and-frequency-division/time-services/ut1-ntp-time-dissemination https://www.nist.gov/pml/time-and-frequency-division/time-se...).
- alexkcd 10y agoThe solution is actually quite simple. [1] 1. Use TAI-UT1 (International Atomic Time, monotonic, no leap seconds, with zero on 1958 Jan 1) for time keeping 2. Define conversion functions that map TAI-UT1 to/from UTC/UT1/etc Use TAI-UT1 when you want to: - synchronize the clocks of a network of computers - calculate time elapsed Convert to UTC/UT1/etc when you want to: - Display a human readable date - You're writing navigation or astronomy software Introducing leap seconds into UTC would then just mean updating the TAI<->UTC mapping function. So all it would affect is how human-readable dates are displayed & navigation/astronomy software is re-aligned to celestial body positions. [1] http://www.stjarnhimlen.se/comp/time.html http://www.stjarnhimlen.se/comp/time.html
- tacostakohashi 10y agoWhat makes you think TAI<->UTC mapping functions are easier to update and synchronize between systems than the time itself? Quite a bit of experience with timezone databases would suggest it's actually not that easy to update this kind of data globally and easily and short notice.
- alexkcd 10y agoGetting the mapping function wrong will only result in displaying a human readable time wrong. Databases, and in fact all systems, should use TAI-UT1 internally and across computers. And only convert to something else when displaying a human readable string.
- ashearer 10y agoThen it would become impossible to store future timestamps in a database and have a stable answer to the question, "on what day will this timestamp occur?" Timestamps around midnight could flip from one day to another unpredictably depending on what version of the leap second database the formatter has. And that wouldn't just affect the leap second day, it would affect every day of every year. That would cause problems for many fields where calendar dates matter (legal and accounting, to name a couple). I expect we'd wind up avoiding the problem by saving dates internally as formatted UTC strings, and be back where we started.