alt Hacker NewsI know my older APC UPSes do weekly self tests, but I guess newer equipment does more frequent self testing? And of course they're all internet-connected meaning clocks are within a few hundred ms of each other.
It also made me think about how many GitHub Actions I have that kick off on Sunday morning at a specific time. I try to vary the time/day for those jobs but I'm guessing there are enough things that kick off at specific time intervals to make an impact at the top of an hour, or at :15, :30, :45...
This is why systemd gives you the RandomizedDelaySec option. (Other cron-like facilities may have similar features, I'm not discussing them here). Set that to N and each time the timer reaches its trigger (say, once per day), its actual start will be up to N seconds after the trigger. E.g. if a once-per-day trigger is at midnight but you have RandomizedDelaySec=300 set, then it will run sometime between 0:00:00 and 0:05:00, with a different actual start time each day.
If enough people used that, with a high enough value of N (say 1800 for jobs that really don't have to start at any particular time), it would greatly spread out the spikes in accidentally-coordinated usage.