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The leap second’s time is up: world votes to stop pausing clocks

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Re: The leap second’s time is up: world votes to stop pausing clocks

#141

Post by ycombobreaker »

hoytech wrote: post #103

In 2015 I was working at a "fintech" company and a leap second was announced. It was scheduled for a Wednesday, unlike all others before which had happened on the weekend, when markets were closed. When the previous leap second was applied, a bunch of our Linux servers had kernel panics for some reason, so needless to say everyone was really concerned about a leap second happening during trading hours. So I was assig…

Sometimes it pays to be the most-prepared among your cohort. In this case, it would have paid so well that your cohort decided to work around it.

It always pays to not be the least-prepared among your cohort. You'll get no sympathy if you're at the back of the pack, you'll just die.

Re: The leap second’s time is up: world votes to stop pausing clocks

#142

Post by vlovich123 »

N19PEDL2 wrote: post #123
bewaretheirs wrote: post #47

Earlier quoted context omitted.

The drift is sufficiently slow that you can fix it with a "leap hour" when needed -- perhaps once every five thousand years. This could be handled for civil/local time via an adjustment in the timezone definitions (something which happens a few times a year today), leaving the underlying UTC timebase unchanged.

Then let's skip the leap hour too: just let UTC and UT1 diverge up to 86400 seconds and compensate that by changing the time zones when needed. Then, when the drift reaches 86400 seconds, the clock times are aligned again. At this point we just need to re-align the dates too, and this can be done by skipping February 29 on a leap year (which should be quite easy to implement in software).

Is that practical? Drift is slow and takes 1 min per century. Let’s say you can live with 10 minutes of drift. That leaves minutes [10-50] which is 4 centuries vs minutes [50-10] where it’s fine which is 2 centuries.

Also, if the problem were time zones, time zones already support non-whole hour shifts, so why not just apply the leap second into all time zones? The reason is that that isn’t what a leap second is. It’s kind of “how much time has elapsed since 1970 midnight” and that number is corrected for with leap seconds. Time zone offsets don’t help you here.

Re: The leap second’s time is up: world votes to stop pausing clocks

#143

Post by coenhyde »

techdragon wrote: post #80

Hot take… Storing anything as UTC was a mistake and we should be using TAI for all storage and computation, only transforming into more human friendly formats for display to end users. This never needed to be a problem except we decided to make it harder to use TAI than UTC and so everything got built up off the backs of legacy bios level hardware supported UTC style clock behaviour, when we should have been using TA…

You've made a very good point. All new software/systems I build will use TAI64. As an industry we should just push this move ourselves

Re: The leap second’s time is up: world votes to stop pausing clocks

#144

Post by zh3 »

nousermane wrote: post #77
adamsb6 wrote: post #50

Currently software has to be built to accommodate leap seconds. They happen frequently enough that you'll find out within a few years whether your software breaks when time suddenly skips forward or backward. If we kick the can down the road such that eventually we'll need to add a leap minute, we're going to end up with software that was never written to expect time to change in such a way, hasn't had a real world t…

You're right, but I'd argue this problem is already here. Thanks to glaciers melting, earth rotation is (temporarily) accelerating. Because of that, positive leap seconds, regular before, didn't happen since 2017 - so there could very well be (recent) software out there that has that code-path broken, and nobody noticed yet. And due to exact same geophysical effect we might see a negative leap second - something that…

Interesting point. Just like a skater pulling their arms in, snow melting and running to lower ground would make the earth spin faster (and let's add in the extra erosion). Sea levels are rising though (due to both thermal expansion and runoff).

Be interesting to estimate the size of the various effects (no doubt I've missed plenty of others) but is it really true that a change in sign of the acceleration of Earth's angular velocity is down to climate change?

Re: The leap second’s time is up: world votes to stop pausing clocks

#145

Post by Konohamaru »

hcrisp wrote: post #115
hoytech wrote: post #103

In 2015 I was working at a "fintech" company and a leap second was announced. It was scheduled for a Wednesday, unlike all others before which had happened on the weekend, when markets were closed. When the previous leap second was applied, a bunch of our Linux servers had kernel panics for some reason, so needless to say everyone was really concerned about a leap second happening during trading hours. So I was assig…

Reminds me of the story of the computer engineer at Data General in Traccy Kidder's nonficion book, "The Soul of a New Machine" [0], who quit after spending weeks toiling away on sub-second timing concerns: > He went away from the basement and left this note on his terminal: "I'm going to a commune in Vermont and will deal with no unit of time shorter than a season." [0] https://en.m.wikipedia.org/wiki/The_Soul_of_a_…

Maybe he should get Stephen Colbert's second-by-second day planner.

Re: The leap second’s time is up: world votes to stop pausing clocks

#146

Post by vlovich123 »

ender341341 wrote: post #126
LaputanMachine wrote: post #111

Earlier quoted context omitted.

> we do hour offsets twice a year, so if an hour off is okay why is 1 second off not? The actual Unix time does not change when the clocks are switched between daylight saving time and standard time. Only the time zone changes. When a leap second occurs, the actual Unix time changes, which can lead to bugs, e.g. when a positive time difference comes back as negative. To prevent such issues, a monotonic clock can be u…

Edit: OK, just re-read some docs, looks like POSIX chose the worst of all options and decrements the timestamp experiencing the same second twice... Wrong info from before edit: Unix time doesn't change either, it's the number of seconds since 00:00:00 UTC on 1 January 1970, though systems may or may not ignore that and set it to match the UTC time.

Yes. It does. Op is correct. A leap second specifically is an adjustment because “how many seconds since 1970” changes because the earth’s rotation isn’t constant speed. UTC tone definitely changes. If it didn’t then you wouldn’t hear anything about it and it would just be transparently folded into your time zone database.

Re: The leap second’s time is up: world votes to stop pausing clocks

#147

Post by Epa095 »

zokier wrote: post #127
ender341341 wrote: post #94

Earlier quoted context omitted.

TAI is monotonic clock, and isn't adjusted for solar time of day, it could be considered universal as TAI would be the same between any 2 points, but UTC is adjusted for earths rotation, so a theoretical mars UTC would end up out of sync with earth UTC. EDIT: info below is incorrect about UTC not being monotonic, as pointed out in thread but is useful for monotonic vs non-monotonic: In UTC you can jump forward or bac…

I'm pretty sure UTC is monotonic too, its unix timestamps that really are the true mess

Yeah you are right, when a leap second is introduced it becomes 23:59:60 (monotonic) in utc, while with unix-time a normal way to handle it is to repeat 23:59:59 twice (non-monotonic).

Re: The leap second’s time is up: world votes to stop pausing clocks

#148

Post by wmf »

Stupulous wrote: post #134
ender341341 wrote: post #129

Earlier quoted context omitted.

How big of a hit is it on the future generation, they can just change their DST, which already happens every few years anyways?

The critical question is whether they'll have to leap forward or fall backward. We simply cannot abide stealing an hour of sleep from our cyborg/transhuman descendants. We'd never live it down.

When longtermism meets leap seconds.

Re: The leap second’s time is up: world votes to stop pausing clocks

#149

Post by friend_and_foe »

jasonwatkinspdx wrote: post #53

I'm' baffled by the section about GLONASS. Russia surely has the ability to decide whether they add or remove future leap seconds?

Of course they do. But government bodies and other institutional bodies incarnated these standards organizations in order to better coordinate with one another, and decided and committed to defering to them a long time ago. Russia is a sovereign state, they can make any decision they want to, but they decided and agreed at some point to defer to this organization for a reason.
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