1. 5
  1.  

  2. 4

    Lots of assumptions/assertions without a lot of evidence. How did 7 of 8 players show up at the correct time? Does Facebook only have out of date time zones on some of its servers? Having different inconsistent data would be a much larger problem, and even undercuts authors thesis. They got the time zone right on 7 servers, so clearly they’re trying to update it.

    1. 4

      Haha, I wrote the article and I was there.

      The rest of the players showed up at the correct time because most are regulars and the game is always at 20:00. The guy who was late was a new guy and a foreigner. So he did not know to ignore the buggy Facebook behavior.

      If you want some evidence, look at this: http://imgur.com/NolBQNk Facebook some places shows the correct time/offset, some places not.

      1. 2

        That answers that - I believed the article, but I had wondered how it happened. :)

    2. 3

      The post seems to imply that the scheduling problems mentioned are because the underlying systems' timezone data was out of date. However, for that to be the case, the scheduled meeting (or game) had to take place where the time zone rules somewhat recently changed and also during the period where the rules were previously wrong. I find that highly unlikely.

      More likely is the software simply calculated the wrong time, either because it thought the user’s current location was somewhere else (e.g., the user is in PST, but the software thought they were in MST), or there’s simply a bug. This means that the remedy described (automated timezone data updates) won’t really help.

      1. 1

        However, for that to be the case, the scheduled meeting (or game) had to take place where the time zone rules somewhat recently changed and also during the period where the rules were previously wrong.

        It is true that the time zone rules somewhat recently changed. The rules were not previously “wrong”.

        Look at this screenshot: http://imgur.com/NolBQNk Facebook shows 18:00 and 19:00 for the same event. It would work correctly if Facebook’s timezone data was up to date.

        1. 1

          Consider that the software responsible for storing and scheduling the event may well be different from the software (and device!) viewing the event. Every part of the system has to be using the same tzdata.

          1. 1

            Sure, but like @tedu says, how come 7 of 8 players (presumably living in the same time zone) showed up on time? And again, did the time zone data change for that particular time zone during the period of that particular game that was scheduled that could possibly have caused a scheduling error for only one player? It seems much more likely that it’s the more typical errors in taking whatever time was stored (hopefully UTC) and processing it correctly (translating it to the user’s timezone).

            1. 1

              Facebook devs don’t see the issue because they mostly sit in a place where the last time zone data change was almost 10 years ago. See my response to tedu about why most people were on time.

              Facebook shows the time for an event in various ways apparently. It seems to sometime show the time entered (the correct time) and sometimes not. This is on the website. There is also the issue of mobile Facebook apps that probably gets timezone info from a phone.

              So usually most people will see the correct time. But because the tzdata is out of date, some places it was wrong.

              (hopefully UTC)

              I wrote this about why future events should not always be stored in UTC: http://www.creativedeletion.com/2015/03/19/persisting_future_datetimes.html In this case, saving the local time plus timezone identifier would have been better than UTC. Facebook could simply show the entered local time without changing it.

              And using up to date tzdata plus the timezone identifier would make it possible to calculate when that time was compared to UTC or any other timezone. This would be useful for the reminders.