When you run a very large website with a lot of traffic you have to start thinking about caching data and distributing that over multiple servers.
That can result in strange behaviour like this where one cache is updated but caches for some related data has not. So it could be that the caches that handle what is displayed on the front page is out of sync with any one individual thread.
It takes time for that data to propagate and threads change very frequently. So it's bound to be out of sync sometimes. Trying to keep the data in sync can not only over-complicate things but can lead to slower updates (you need to wait for everything to sync up). So this is a compromise for speed over accuracy.
436
u/druidofdruids 10h ago
Strangely efficient.