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Everyone is treating this as some idiosyncratic proposal of Facebook's, but removing leap seconds is a mainstream position. Representatives of the US, China, F
by jefftk 4y ago
Everyone is treating this as some idiosyncratic proposal of Facebook's, but removing leap seconds is a mainstream position. Representatives of the US, China, France, and a majority of other countries were in favor of this when it was discussed at the 2015 ITU meeting [1] though the UK and Russia's were not. This has been under discussion since at least the 2003 ITU meeting in Turin.
[1] https://www.nature.com/articles/nature.2015.18855 https://www.nature.com/articles/nature.2015.18855
- ncmncm 4y agoYes. Leap seconds are just a thoroughly bad idea, from any angle. Yet, not nearly so bad as Google's approach: no leap, but a 24-hour smear, during which 24 hours they are out of sync with literally everybody else in the world.
- joerichey 4y agoFor future leap seconds, Google (including GCP) are planning to use a "standard" smear (https://developers.google.com/time/smear https://developers.google.com/time/smear). This is also the same smear used by AWS. It seems like if the ITU decides to keep the leap second (a bad idea, in my opinion), the large infrastructure providers will just use the same standard smear for their clocks.
- ncmncm 4y agoThey will be wrong all day long, not just for one second. AWS will be, too, evidently. Few others will do anything so idiotic.
- guipsp 4y agoThey will be wrong by at most one second. And being wrong doesn't even matter, as long as everyone (or rather, all your servers) agree.
- fanf2 4y agoAt most half a second, in the middle of the smear at midnight when the leap second is applied. The Facebook smear is asymmetrical so it starts off 1 second off just after the leap second, and subsequently corrects itself. [ The reason Google and Amazon use a linear smear is because NTP clients try to measure the rate difference between their local clock and the reference clocks; if that is different every time the NTP client queries its servers, it will have trouble locking on and accurately matching the smear curve. You can mitigate this somewhat by fixing a higher NTP query frequency, but that’s a heavy-handed fix for an engineering mistake. ]
- staticassertion 4y agoWhat are the practical issues with potentially being wrong for one day by at most one second?
- a9h74j 4y agoI assume finance and control systems to start. I might be helpful to have a fallback time-ordering algorithm not dependent upon one monotonic clock, but then you might have a rarely-used fallback to have bugs in, I imagine.
- Too 4y agoWhat are the practical issues for finance and control systems?
- denton-scratch 4y agoFor finance, it matters what order events occur in. I've never messed with control systems, but I suppose similar issues arise.
- GoblinSlayer 4y agoOrdering can be solved by a mutex.
- lifeisstillgood 4y agoThey are "wrong" technically but they won't be "wrong" more than a packet getting routed transatlantic would be - so if I send two packets from my laptop in London - one to AWS in London during the smear and one to another laptop in NYC, and timestamped the packets arrivals, the time stamps would likely be similar. Yes "wrong" but if it's a problem then it's a problem you have with speed of light. The answer is to find a different / reliable method of ordering.
- mattnewton 4y agoDidn’t Google change their smear to 24 hours because it was what AWS and some other internet time servers used?
- ncmncm 4y agoYes: which shows that the skew was a problem. Eliminate UTC leap seconds, and the overwhelmingly worse smear problem vanishes too.
- deleted 4y ago[deleted]
- oittaa 4y agoAWS does exactly the same. > The AWS Management Console and backend systems will NOT implement the leap second. Instead, we will spread the one extra second over a 24-hour period surrounding the leap second by making each second slightly longer. https://aws.amazon.com/blogs/aws/look-before-you-leap-the-coming-leap-second-and-aws/ https://aws.amazon.com/blogs/aws/look-before-you-leap-the-co...
- ncmncm 4y agoI.e., be out of sync all day long with literally everybody except Google.
- zsims 4y agoAt that point, how much of the internet is that?
- ncmncm 4y agoAlmost everybody. AWS and Google would like to think the internet is just them, but they are a tiny little bit of it.
- nvr219 4y agoNo, you don't understand, Amazon and Google will be right, and everyone else will be out of sync with THEM.
- Gigachad 4y agoWhat is the consequence of being a fraction of a second out of sync?
- londons_explore 4y agoAlgorithms that involve 'i did this thing at this time, everyone else should wait for that time to have passed before continuing to ensure correct ordering' (ie. Many database systems) will dramatically slow down. Systems that use atomic clocks might have been able to do 10,000 transactions per second will suddenly only be able to do 2 transactions per second if they contain a node that doesn't use the same smearing.
- deleted 4y ago[deleted]
- Thorrez 4y agoMeta also smears, as mentioned in the article. The article calls smearing "common practice". I think smearing can help reduce outages. The article mentions that reddit and Cloudlare had outages caused by leap seconds when they weren't smearing. I think it's a tradeoff between being standard and avoiding outages. Disclosure, I work at Google.
- 0xCMP 4y ago> “If we have an offset from solar time, it is not extremely important,” [...] “We are already shifted by one hour in summer compared to winter time. Are we affected because of that? > Official time would slowly move out of sync with Earth’s rotation, but — given that it would take thousands of years to accumulate a difference that is greater than the kinds of shifts already caused by changing the clocks backwards and forwards for daylight savings time I think this argument: that we're syncing to atomic clocks and keeping in sync with the sun isn't so important should have been included in the post. I stand by my earlier comment that it felt like a hack, but aligning with SI unit of time + atomic clocks is, I think, far superior.
- yieldcrv 4y agoFacebook should make another trade group so they can post well thought out proposals under that group’s name without the ad hominem distractions of being Facebook Their name, Meta and Zuck’s name is too sullied for good faith discussions
- jefftk 4y agoThen the comments here would be calling out FB for making sneaky front groups to disguise their involvement!
- stjohnswarts 4y agoAs someone who has had to deal with it in embedded, I'm all for removing it and finding a better way.
- nullc 4y agoGenius move: figure out what proposals you dislike and get facebook to advocate for them...
- twic 4y agoCurious as to the reason for the UK's position, given that UK timelords have a strong track record, but this: > Britain’s argument is largely based on the desire to keep a link between official time and Earth’s rotation, says Peter Whibberley, a metrologist at the National Physical Laboratory in Teddington, UK. just seems silly. Bit more from Whibberley here [1]: > There's no agreement internationally. Some countries favour ending leap second because they do cause problems. Some software in particular has great difficulty handling leap seconds. The simplest solution is simply to end them. > But other countries say it's important to maintain the traditional link between timekeeping and the Earth's rotation and arguing we should keep leap seconds until at least we understand much better the long term consequences of ending them. > Well, I'm part of the UK's delegation at this grand meeting that would discuss the issue in November of this year. So, it's my job to argue the UK's position but from a personal point of view, I don't have any stronger sympathies one way or the other. They're both very good arguments and the problem is, no compromise position. You had to keep leap seconds or you end them. Whatever happens, it's going to be very interesting. > The UK government has considered the issue and it's theory is we should maintain this traditional link between our timekeeping and the Earth's rotation. Some random googling turns up a document [2] which says: > The UK has previously consulted official bodies and agencies with an interest in precision timekeeping. None of these authorities reported significant problems arising from leap seconds, while some scientific institutions reported strong support among their memberships for retaining leap seconds. With a reference to the article 'A British perspective of the future of Coordinated Universal Time' [3], which is longer, but doesn't really contain any more substantive points in favour of leap seconds. Looking for that also led me to a more detailed presentation on the subject [4]. Hmm. [1] https://www.thenakedscientists.com/articles/interviews/what-are-leap-seconds https://www.thenakedscientists.com/articles/interviews/what-... [2] https://sciencewise.org.uk/wp-content/uploads/2021/03/DR-5.pdf https://sciencewise.org.uk/wp-content/uploads/2021/03/DR-5.p... [3] p. 51 of https://www.itu.int/bibar/ITUJournal/DocLibrary/ITU011-2013-07-en.pdf https://www.itu.int/bibar/ITUJournal/DocLibrary/ITU011-2013-... [4] https://www.itu.int/dms_pub/itu-r/oth/0a/0e/R0A0E0000960014PDFE.pdf https://www.itu.int/dms_pub/itu-r/oth/0a/0e/R0A0E0000960014P...