[lazide]

Every serious Java based Web App I've ever worked on had a prewarm step or continuous probing setup for exactly these issues. It isn't unique to Java either - lots of languages have lazy library or dependency loading, or runtime caching of external files or the like that you want to do before you start serving requests.

[kimi]

Or a cache to be loaded. In related news, "Continuous delivery makes caching an anti-pattern".

[p2t2p]

Not really. You move cache off-heap in Java terms and it persists it between restarts. One Russian social network has about 60 gigabytes of stuff cached that way