Caching for TWiki, Part II

The current code implements some storage backends now. Before we only had a Cache::Memcached based backend which is great on your own servers, but not applicable for little TWiki installations in hosted environments where you are not allowed to launch daemon processes.

What we have right now is

• Cache::Memcached
• Cache::FileCache
• Cache::SizeAwareFileCache
• Cache::MemoryCache
• Cache::SizeAwareMemoryCache

I did not make use of the shared memory variants as they are quite limited in their storage capacity. The Cache::FileCache is said to perform as fast anyway, but does not have those restrictions. For html page caching the first two variants are the most interesting. Basically you can forget Cache::SizeAwareFileCache, and it's only there for completeness. This backend simply performs too much maintenance on its own behalf to be usable for TWiki. The Cache::SizeAwareMemoryCache, however, is comparably fast purging out pages, as it does not suffer from the extensive disk IO that happens in the Cache::SizeAwareFileCache. Both memory variants are not able to share their cache among several processes, and thus are obviously out for html page caching. The current WikiRing blog runs on a Cache::FileCache now. It used the Cache::Memcached backend for quite some time. But as I am low on RAM but not on disk space on this server anyway (anybody out there that likes to sponsor a bigger server or more memory?) I switched to the file-based variant, which performs quite well.

I still owe you performance statistics, hard facts.