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Leap Second May Be On the Chopping Block (ieee.org)

szotz writes: The days of 61-second minutes may be coming to an end. The World Radiocommunication Conference is meeting for nearly the entire month of November, and one of the hot-button issues is what to do about the leap second. The addition to UTC is supposed to keep atomic time aligned with Earth's rotation, but past leap seconds have caused server crashes, and some are worried that future problems could be even worse. Going into the conference, it doesn't look like there's much of a consensus on what to do. One official is expecting weeks of debate.

22 of 291 comments (clear)

  1. It's not the Earth's fault by plover · · Score: 5, Insightful

    So people write crappy code and rely on it without adequate fault tolerance strategies and that's somehow the problem of people who measure time? I think not.

    --
    John
    1. Re:It's not the Earth's fault by Anonymous Coward · · Score: 2, Insightful

      There will certainly be lots of problems if and when software is required to cope with relativity of time.

      But, whenever that does happen, it is certain there will be people complaining the old code is crappy because it does not take the necessary details into account.

    2. Re:It's not the Earth's fault by rainmaestro · · Score: 5, Interesting

      This is a large part of the problem. More often than not these issues stem from people trying to roll their own time handling code / int'l address code / i18n / etc rather than using one of the standard (and well-tested) libraries available in their language.

      Time is hard to get right, addresses are hard to get right, i18n is hard to get right. Don't roll your own. There's a thousand edge cases you haven't accounted for.

    3. Re: It's not the Earth's fault by martin0641 · · Score: 2

      Except that then nothing can be accurately measured. It might fool the humans, but if you need a timer to go off with precision it's hard to make that happen if you are adding microseconds to the time just so fix the time relative to a rock slimming around a ball of hot gas. Sometimes 60 seconds really needs to be sixty seconds.

    4. Re:It's not the Earth's fault by 0123456 · · Score: 2

      This is a large part of the problem. More often than not these issues stem from people trying to roll their own time handling code / int'l address code / i18n / etc rather than using one of the standard (and well-tested) libraries available in their language.

      Uh, no. Not in the least.

      Most of these issues stem from operating system bugs which are only triggered by leap seconds, which can't easily be tested before the leap second happens. We had to get special firmware from our GPS manufacturer to get it to send out NTP packets that simulated a leap second, so we could do that.

      And even when you have backup systems, they fail at the same time, because the leap second happens everywhere at the same time.

      They're a freaking disaster, and anyone who cares about them can deal with them in their code, rather than forcing everyone to deal with them.

    5. Re: It's not the Earth's fault by aaron4801 · · Score: 5, Insightful

      One second is "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom."
      Everything else is derived off of that. Why does one minute every few years have to be redefined just to keep "one day" relatively constant? They've effectively got two units of measurement that conflict with one another. We let "one year" drift enough that it only needs to be corrected once it's off by a whole day. Why not let those seconds accumulate and have a second leap day every hundred thousand years or so?

  2. Let me think about it for a second .... by pollarda · · Score: 2

    While I'm sympathetic for all the folks who want to drop the leap second, given an appropriate amount of time the difference will add up. It seems to me the problem is quite simple which is to publicize the leap second a bit more than it is now. It is an education issue -- at least no more or less than leap days and that seems to work just fine all in all.

    Perhaps Facebook can create a viral leap second post. Much better than viral kitty posts.

    1. Re:Let me think about it for a second .... by Anonymous Coward · · Score: 2, Funny

      Pass a law saying all bars / taverns / pubs are not allowed to charge money for drinks served during the leap second. It'd get plenty of publicity.

    2. Re:Let me think about it for a second .... by Anonymous Coward · · Score: 5, Interesting

      The problem with leap seconds vs. leap days is that leap seconds do not follow a regular pattern. It's fairly simple to write code that follows the leap year rules: February 29 occurs when (year mod 4 == 0 and year mod 100 != 0) or year mod 400 == 0

      The timing of leap seconds, on the other hand, are chosen on a case-by-case basis by some standards body (IERS) and announced, usually with only about six month's notice. Thus hardcoded rules for leap seconds are not a good idea, and you have to have some means of distributing leap second announcements to all systems where clock accuracy is critical. Either that or you accept a one-second margin of error, don't count the leap second and correct the clock later.

    3. Re:Let me think about it for a second .... by Xylantiel · · Score: 2

      Hopefully you realize that leap seconds are not "chosen by a standards body" per se, they are actually measurements of the slow-down of the earth's rotation and the standards body just decides how to schedule them. As another poster said, if you don't need to know the time of day, don't convert to UTC, just use a time standard that doesn't have leap seconds. The problem here is ignorant people who don't realize that time of day is not easily derivable from time-since-epoch. Changing from leap seconds to leap minutes just allows them to be ignorant longer, which I would argue is a bad thing.

  3. Re:Conspifrosty by Tablizer · · Score: 4, Funny

    I like to hang out at Area 15. Less security and you glimpse an occasional dyslexic alien.

  4. Re:Obvious answer by Anonymous Coward · · Score: 2, Interesting

    Midnight is always 00:00. There is no such hour as 24:00, but alas the ID10Ts at apple think there is and put one into Yosemite.

  5. Re:Computers have some solution right? by Archangel+Michael · · Score: 2

    The problem isn't the system, it is the software and databases that require millisecond accuracy.

    The problem is that time is not as linear as we think it is. Even accurate clocks can start having time shifts in relation to each other. This is all spelled out in Physics and is (or at least, should be) well known.

    We need to change how we keep track of time, in a way that isn't linear.

    --
    Agent K: A *person* is smart. People are dumb, stupid, panicky animals, and you know it.
  6. I'm majorly confused by holophrastic · · Score: 4, Insightful

    In my 35 years, I've always seen time as a counted measure of how much time has passed since I started counting. I seem to be forever learning that's my novel idea.

    Why should I care where the sun is, where the moon is, where the earth is, with respect to time? If it's winter, I can start work at 9, I can start at 10, I can start an hour after sunrise. I don't need to adjust my clock to start work at the same clock-display every day. I see nothing wrong with a company that has different business-hours by the season.

    Similarly, since I'm not in the old west, I don't care if "high noon" is an noon, or 1, or 1 second after noon. I've never determined the time based on the sun.

    Last I checked, we have perfectly wonderful time-keeping and gps devices these days. So ocean ships and submarines no longer need a sextant and a chronometer to figure out when and where they are.

    So here's my petition. I'd like time to always move forward, and the same rate of 1 second per second. I'd like it to not jump, leap, crawl, rewind, fast forward, restart, end , or eject.

    Shit, I just realized that I'm not 35 years old. Or I am 35 years old, but not when measured in seconds. Wait for it...ok, now I'm 35 years old. Phew.

    1. Re:I'm majorly confused by Mr.+Slippery · · Score: 2

      Why should I care where the sun is, where the moon is, where the earth is, with respect to time?

      Because the primary function of time since the dawn of civilization has been to allow human activity to synchronize with the position of the sun, from planting seasons to night watches.

      If it's winter, I can start work at 9, I can start at 10, I can start an hour after sunrise.

      If you never leave the server room, perhaps. Most human beings have lives that are affected by sunlight. At the very least commuting in light or dark matters. Construction, farming, and many other jobs are deeply affected by daylight conditions. And some of us actually just like to go and play in the big blue room while it's blue. (Try it sometime!)

      --
      Tom Swiss | the infamous tms | my blog
      You cannot wash away blood with blood
  7. If you can't deal, don't use UTC by oneiros27 · · Score: 3, Insightful

    There are plenty of systems for time that *don't* involve leap seconds.

    If your system's too crappy to be able to deal with leap seconds or you don't have a way to update them, use TAI or GPS time.

    Don't screw with the definition of UTC just because you can't handle the complexities of it. It's not like someone's forcing you to use UTC, UT1R, or one of the other UT systems that are specifically intended to deal with issues of local noon.

    (disclaimer: I work for a group that deals with solar observations*)

    * and even one of them almost screwed the pooch and didn't distribute the update for the June/July 2015 leap second until 3 days before it happened ... and of course it was compiled in (for speed, they claimed**) rather than be an external file.

    ** if it really was for speed, then they need to flip their giant if/then structure so it starts in the present and walks backwards in time, rather than how they're doing it now where it runs dozens of tests that will always fail for a spacecraft that wasn't launched 'til 2010.

    --
    Build it, and they will come^Hplain.
  8. Eh? by wonkey_monkey · · Score: 2

    The days of 61-second minutes may be coming to an end

    Wait... are they getting rid of days, seconds, or minutes?

    --
    systemd is Roko's Basilisk.
  9. Leap-Seconds Existed More Than 45 Years Ago by DERoss · · Score: 5, Insightful

    Leap-seconds were properly handled in computer software before most of today's software engineers and programmers were born.

    Back in 1969, I started working on a software system that already handled leap-seconds quite smoothly. At that time, keeping UTC aligned with the rotation of the earth involved introducing fractional seconds and also having UTC seconds NOT the same duration as atomic seconds (TAI). In 1972, this was simplified by having UTC seconds exactly the same duration as TAI seconds and (after an initial fractional leap) introducing only leaps that were full seconds. The software in the system on which I was working DID NOT HAVE TO CHANGE!!.

    Internally, the system on which I was working -- which evolved and continued in use to operate military space satellites for over 20 years -- kept all time in TAI, which never has leap-seconds. A relatively small routine converted in either direction between UTC for displays and TAI for internal time. Another small routine converted from UTC to UT! to sidereal time, the latter more closely reflecting the rotation of the earth, which is gradually slowing and also has predictable periodic fluctuations. The purpose of all this was that we needed to know very accurately the spot on the rotating earth directly under the orbiting space satellite. The position of the satellite was known in TAI while the surface of the earth was rotating very closely to sidereal time.

    Also note that the network time protocol (NTP) also accounts for leap-seconds and has done so for decades.

    I can only conclude that the current attempt to do away with leap-seconds is a result of lazy software "professionals" trying to shift blame for their ignorance about leap-seconds.

  10. They want to shift the problem to someone else. by NeoMorphy · · Score: 2

    Incompetent people like to shift problems to someone else. They're already trying to shift problems like "national debt", pollution,and "climate change" to the future generations and now they want to shift another problem to a future generation.

    I would prefer better coding and testing standards to be the norm. At the moment, every time a problem occurs because of a "leap second" it's noticed and fixed with a reminder that this is something to be watched and tested for. I would like to think that handling it would become part of the standard QA procedures, actually it should have already been part of QA, it's not new, this has been happening for over 40 years!

    If they think a "leap second" is a big deal then a "leap minute" or "leap hour" is going to really cause problems. They'll have longer periods of time for more bugs to accumulate and when they happen everything will have problems because either they'll fail or something they depend on will fail.

  11. Re:So, let's discuss this.... by msauve · · Score: 2

    "How close do we need to be to the astronomical time?"

    For UTC, within 1 second. That's what it was created for, to follow Sol, just like the other UTx timescales.

    For those who don't care, there are timescales which don't have leap seconds - TAI, GPS, etc. Use them instead of trying to redefine UTC to be completely decoupled from its intended purpose.

    This issue isn't leap seconds, it's lazy or stupid programmers or committees who don't or won't understand how UTC works.

    --
    "National Security is the chief cause of national insecurity." - Celine's First Law
  12. get rid of winter time by stooo · · Score: 2

    in the same time, we could get rid of summer/winter time change

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    aaaaaaa
  13. Circadian rhythm by tepples · · Score: 5, Informative

    We let "one year" drift enough that it only needs to be corrected once it's off by a whole day. Why not let [86,400] seconds accumulate and have a second leap day every hundred thousand years or so?

    Because sunlight levels over a day control more recurring human biological processes, such as alertness, than any natural phenomenon with a year's period.