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Tell HN: Sudden Chile daylight savings time rules change causes chaos

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Re: Tell HN: Sudden Chile daylight savings time rules change causes chaos

#11

Post by rmujica »

Chilean here. Unfortunately our governments have had the bad habit of changing the date DST starts on every two-three years, and that wreaks havoc everywhere in the country. We are kind of used to having a couple of days where we assume everyone will run an hour late because of this.

I just hosted some Peruvian friends this week and were amazed at the kind of power the government wields just by having the ability to change our timezone.

We should be placed on GMT-5, but for a couple of reasons we are on GMT-4 and GMT-3 for DST. Our country is so long that some places on the north have normal length days but on Patagonia days are shorter and they prefer to be on DST all year long (and since some years ago we have a different timezone for that area).

Re: Tell HN: Sudden Chile daylight savings time rules change causes chaos

#12

Post by gerikson »

toomuchtodo wrote: post #4
gerikson wrote: post #2

In my previous job we had to deal with sudden DST changes in Jordan, Russia, Turkey... it's amazing politicians don't realize what a big deal sudden changes can be. Edit it appears the switch was delayed due to the constitutional referendum. Turkey had national exams as a reason, I believe.

I would love to read a blog post from you on this topic!

Thanks, maybe I'll try to put one together!

Re: Tell HN: Sudden Chile daylight savings time rules change causes chaos

#13

Post by baggy_trough »

iwwr wrote: post #3

Some call it "chaos", others might call it "badly written software".

Not all, or most, software that deals with time can be updated and deployed with less than 30 days notice. This is simply a grotesquely impractical policy change.

Re: Tell HN: Sudden Chile daylight savings time rules change causes chaos

#15

Post by sjsdaiuasgdia »

hilbert42 wrote: post #5

No doubt changing daylight saving rules at short notice is difficult but we should be asking ourselves why is it so. The major problem adjusting to daylight saving should be as it's always been - that of human adaptation to the sudden change of time. That our computers cannot adapt at a moment's notice simply says there's fundamental problem with their design. Moreover, the problem should have been long solved by now…

Far more coordination with this than something like Y2K. This is a government deciding the rules of time have changed in some way. Y2K, the rules of time didn't change, but a pattern of implementation decisions frequently used over the previous few decades broke down.

A system that needs to know about the rule change has to actually receive it in some way. It has to be connected or the update has to be brought to it. That alone creates a lot of systems that cannot react to a change like this at a moment's notice.

You know when Y2K and Y2038 hit relative to yourself because they're numerical rollovers that can be computed from your current time. You can't know when the congress of Whereveralia has decided to change DST rules without someone or something telling you.

Re: Tell HN: Sudden Chile daylight savings time rules change causes chaos

#16

Post by hilbert42 »

DougN7 wrote: post #7
hilbert42 wrote: post #5

No doubt changing daylight saving rules at short notice is difficult but we should be asking ourselves why is it so. The major problem adjusting to daylight saving should be as it's always been - that of human adaptation to the sudden change of time. That our computers cannot adapt at a moment's notice simply says there's fundamental problem with their design. Moreover, the problem should have been long solved by now…

In my opinion it’s because it’s so easy to assume a day has 24 hours. Coding for an occasional day that has 23 and another with 25 just doesn’t occur to most people.

Yeah, like so. But these changes aren't just 'one-offs', they're in fact common enough for a streamlined procedure to be in place - yet it's not.

Re: Tell HN: Sudden Chile daylight savings time rules change causes chaos

#18

Post by chrismorgan »

This is not novel. Look through the tzdb news and you will find many instances of similar and considerably shorter periods of notice.

Just to pick a couple from last year that are unambiguous and well-documented (most you’ll have at least a bit more trouble finding first-party announcement of):

2021d: Fiji gave a month’s notice on suspending DST for the season.

2021b: Samoa gave less than a week’s notice on cancelling DST.

I have a feeling there was a less-than-two-days’ notice a few years ago, but can’t be bothered hunting for it. But there are many more of things like “eh, we’re shifting the start or end by a day or two or a week or two, with less than ten days’ notice”.

Re: Tell HN: Sudden Chile daylight savings time rules change causes chaos

#19

Post by thro388 »

amelius wrote: post #10

I like this chaos-monkey approach to politics, and we should do it more often. Now let me slide this handle that increases taxes on HFT and see what happens.

Even better, let's lock everyone at their homes with 3 hour notice at 2 AM...

Re: Tell HN: Sudden Chile daylight savings time rules change causes chaos

#20

Post by spiffytech »

This kind of thing is why it's important to store user-specified future dates as local time + IANA zone name.

If a user wants a calendar event at 9am, they probably still mean 9am after accounting for time zone or DST changes.

Storing dates as UTC is appropriate for dates in the past, or future dates that a user will never expect to happen at a certain wall-clock time.

(An IANA zone name is something like America/New_York, and not EST or UTC-05:00)

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