If you didn’t already know, there is a famous quote in the software world attributed to Phil Karlton that goes like this;
There are only two hard things in Computer Science; cache invalidation and naming things.
Whether or not there are other, unmentioned difficulties in the field, cache invalidation is an absolute nightmare. Everytime I rebuild the solution for the application I am working in my day job, it rebuilds the entire cache, which takes 15-20 minutes. Before I can see whether any of my changes have taken effect. Yuck.