"Our customers aren't in UTC" is often a compelling reason.
People generally expect things like usage limits to reset overnight, not at UTC midnight, and these are often implicitly tied to (the result of) batch jobs.
Financial jobs, including billing, is another big category.
Having tried many times to use local time instead of UTC to make life simpler for myself, I really don't think it's ever a good idea.
Better to localize times for users on the client-side based on their local settings, IMHO
For quotas and usage limit resets it can be a little harder, but if it's a cron job anyway, my initial approach would be to just schedule it for a time that is close to midnight for the area your customers are in.
> "Our customers aren't in UTC" is often a compelling reason.
This doesn’t work as soon as you become a global business… because if you tell a customer in Asia that it resets at midnight in some US timezone, what are they going to think?
Many people will accept UTC because it is the international standard. Everyone will accept “let each customer pick the timezone that works best for them”. Saying “I’m going to use a US timezone because that is easiest for our US customers” risks sending a message to your (now or future) global customers that you view them as second-class citizens.
Really depends on your market and customers. Especially in the financial industry, local time zones (often of a given currency's central bank's main branch, a primary regulator etc.) are often very, very entrenched.
> Many people will accept UTC because it is the international standard.
I really wish that were true universally...
And I do think that UTC is actually somewhat Eurocentric! From personal experience, it's significantly easier to mentally add/subtract one or two hours (modulo 24) than 7 or more.
> Saying “I’m going to use a US timezone because that is easiest for our US customers” risks sending a message to your (now or future) global customers that you view them as second-class citizens.
Definitely, but on the other hand, I do think that picking your head office's time zone as the "canonical" one for resetting quotas etc. has some merit as well, if only because it makes the concepts of "today" and "tomorrow" work a bit better. (UTC midnight might be very unintuitive to both you and your customers.)
> Definitely, but on the other hand, I do think that picking your head office's time zone as the "canonical"
What happens when you move your head office to a different time zone? e.g. Oracle moved their HQ from California to Texas (and have announced a further move to Tennessee, although last I heard that still hasn’t happened)
What happens when an M&A happens and you are now part of a much larger enterprise with a different HQ timezone, and systems with wildly inconsistent configured timezones due to having acquired multiple companies which had HQs in different time zones and all of which configured everything to use their HQ time?
> UTC midnight might be very unintuitive to both you and your customers
I live in eastern Australia, UTC+11 at the moment (UTC+10 during Southern Hemisphere winter). Right now, resetting stuff at UTC midnight means at 11am my time, resetting stuff at US Eastern midnight means at 3pm my time - roughly equal in potential inconvenience, but I’ll be much more forgiving of the first than the second.
> And I do think that UTC is actually somewhat Eurocentric! From personal experience, it's significantly easier to mentally add/subtract one or two hours (modulo 24) than 7 or more.
For me, add/subtract 10 is pretty easy… and then just one more during DST. Does that make UTC “Australia-centric”? Or Guam-centric or Vladivostok-centric? (both of which are also UTC+10)
That does not require setting the server to local time. Run the cron job every hour. Before starting the script, check the time and compare it to the last saved execution time. If the day has changed, do stuff and save the new date, else exit. This also happens to be more resilient to server downtime around midnight.
> Before starting the script, check the time and compare it to the last saved execution time. If the day has changed, do stuff and save the new date, else exit.
That sounds a bit like reimplementing a scheduler inside the scheduled task (which is ok if you don't trust your scheduler, but I'd avoid it if at all possible).
Except downtime can start during execution. So for many types of jobs...
- Check if run today, exiting on "yes"
- Run
- Update the last-run-on date
What is "today"?
Hopefully just a datetime recent enough that the job does not currently need to be (re-)run.
But as soon as one job needs another to complete first, or two jobs shouldn't be run at the same time - things start getting messy.
> Hopefully just a datetime recent enough that the job does not currently need to be (re-)run.
I can think of several ways to mess that seemingly trivial calculation up just from the top of my head. (Consider changing timezones, increasing the interval the job is running to within half a day of scheduling period etc.)
Always set the servers to UTC. Convert the time to local time for display, but store in UTC.
The reporting job should be run from a server on UTC and on UTC time. The report itself can convert to whatever is local time.
That doesn't fix the problem of "my quota reset (or reporting job) gets shifted by 1 hr when daylight saving time changes".
The reporting job should be run from a server on UTC and on UTC time. The report itself can convert to whatever is local time. This is exactly what I said above.
That works if all your consumers of the report are indifferent to it arriving at a different time half of the year.
All of yours might well be, but you can't generalize that assumption to every domain and scenario.
If you want an email of the report to send out at 9am locally. Generate before and send to everyone based on timezone.
> Generate before and send to everyone based on timezone.
How are you going to do this? Clearly cron (with timezone set to UTC) doesn't work for this so you'll need another system. In that case why not have that multi-time zone scheduling system run your script?
You don’t want a report to include 25h or 23h twice a year just to be able to send it at some distinct local time.
I absolutely want some daily business reports to cover 25 hours on one day of the year and 23 on another, since that's how long a calendar day is in local time in every place that has DST shifts.
Yes, that's exactly what I want. Everything shifts with dst - business processes, people's working hours, ach windows, ...
The report can run at whatever time you want it to run at. But this solution solves the issue of the report running 2x or not at all.
You could have the reset script check the timezone of the user before actually performing the reset, and have this script run at least once an hour to make sure you get close to accurate for most people (some timezones only differ by less than an hour though!).
But also, if the user can change the timezone themselves, now you have a condition where the user could keep their quota at bay for a very long time (if not forever) if they keep changing their timezone accordingly.
Do you actually care if the requests were made on some specific calendar day? Or do you just want to make sure that heavy users are paying more and/or people aren't abusing your system?
Instead of tying your quotas to calendar days in some specific time zone, tie them to a rolling 24 hour usage period. Even better: use a rolling hour.
> That doesn't fix the problem of "my quota reset (or reporting job) gets shifted by 1 hr when daylight saving time changes".
How hard is to convert the UTC time to user's local time and perform quota reset?
I mean you should be doing this anyway. Even if you store everything in PST or EST or CST, you never know when you'll get customers from another part of the world and then you'll have to do this anyway. So why not do this already?
>Even if you store everything in PST or EST or CST, you never know when you'll get customers from another part of the world and then you'll have to do this anyway. So why not do this already?
1. allowing users to change their timezone and tying it to when their quota reset sounds like a great way to add more edge cases and complexity. For instance, does messing with your time zone mean you can get your quota reset multiple times a day?
2. Not everyone operates some sort of global b2c SaaS that's timezone agnostic. For many enterprise backoffice tasks "6am HQ time" is far more reasonable than "6am/7am, dunno depends on whether daylight saving time is on or not". In this case having a server set to the HQ's timezone makes far more sense than doing UTC and trying to work around daylight saving issues.
> How hard is to convert the UTC time to user's local time and perform quota reset?
Probably roughly as hard as writing a timezone-aware scheduler that considers all edge cases around daylight savings time, i.e. probably possible but I'd try fairly hard to see if I can get around it.
One way of getting around it is to run your batch jobs in your "primary business timezone". Sure, you might outgrow that concept eventually, but many companies never do, and in that sense "running on UTC" seems similarly aspirational in spirit (albeit at a much smaller scale) to starting with high scalability.