Cache::Memcached -- performance question

[Thilosophy]

Fellow Monks,

I just stumbled upon Cache::Memcached, which looks very interesting for use in load-balanced web applications. Before starting my own experiments with it, I thought I'd ask the Monastery about their experiences with memcached.

I am wondering

1. how much slower it is versus an in-process-memory cache (which probably differs for small and large data)
2. how much slower it is versus shared memory
3. if it makes sense to use it for HTML::Template's cache (replacing in-memory or shared memory)
4. if it is possible to share data between languages (say Perl and Java) -- probably not, seeing that it uses Storable
5. how reliable people have found it to be
6. any caveats you need to be aware of

[perrin]

It's about the same speed as a simple MySQL query on a single unique key. It's much faster than Cache::Cache and most of the other caching modules out there. It's about half as fast as BerkeleyDB or Cache::FastMmap. It's not even close to the speed of an in-process memory cache.

It is possible to share a cache server between multiple languages if you make both languages serialize in the same way. Memcached just stores bytes, so it doesn't care.

Some large sites use it, so you can probably expect it to be reliable. Check the mailing list for anecodotes and testimonials.

[samizdat]

I tried setting it up a while back and was unsuccessful in getting it to work in my configuration. I use Embperl as my templating system, and, for some reason, Apache::Session::memcached would not cooperate with Embperl. Nobody here (PM) had any answers, neither the embperl or memcached lists was helpful, and I had to move on. I was able to access the memcached in other ways, just not through embperl. See this node.