I've been reading the recent blogpost "Winding down my Debian involvement" by Michael Stapelberg. Sad details aside, it's been mentioned that within Debian infrastructure batch jobs run four times a day at XX:52 UTC:

When you want to make a package available in Debian, you upload GPG-signed files via anonymous FTP. There are several batch jobs (the queue daemon, unchecked, dinstall, possibly others) which run on fixed schedules (e.g. dinstall runs at 01:52 UTC, 07:52 UTC, 13:52 UTC and 19:52 UTC).

Is there a reason to choose XX:52 UTC exactly and not to use time rounded to the nearest hour, e.g 02:00, 08:00, 08:00 and 14:00?

Should I also start my cron jobs slightly before the new hour starts, or this was a random choice by the Debian team?

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    One of the main reasons I can think of for this convention is that if the convention is to pick a random number of minutes then there will be a spread of jobs being kicked off over an hour. If the convention is to put them exactly on the hour then servers will grind to a halt every 60 minutes with everything kicking off at once. – Philip Couling Mar 11 at 10:26

It is not random, and it is something that a system administrator should think about.

Notice that your cron.hourly, your cron.daily, your cron.weekly, and your cron.monthly are all run at different times. These times have varied over the years, and have been moved back and forth, because these jobs interact with one another, sometimes badly. The same is true of other Debian infrastructure.

This is a thing to think about in general with scheduled jobs running in batch. (It's not just cron jobs, but this sort of job in general. And it's not just Debian.) The job that cleans up files might interact with the job that scans the filesystem for stuff, which might interact with the job that makes temporary files as it is working, …

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