[chubot]

Not that there's no benefit, but just that it's more complicated in a distributed system.

Certainly caching is vital to many distributed systems, but it has to be done from a systems perspective. In my experience a lot of caches are just slapped on top of individual components without much thought, and without even some basic monitoring of what the hit rate is. I think it helps to actually measure what the cache is doing for you -- but this is more work than adding the cache itself.

And I agree with another poster in that I've seen many systems with caches papering over severe and relatively obvious performance problems in the underlying code.

I was thinking of this Google publication which outlines some problems with latency variability: http://www.barroso.org/publications/TheTailAtScale.pdf

Interestingly they didn't seem to list caches as one of the causes; they list shared resources, cron jobs, queuing, garbage collection, power saving features, etc.