[Zope-dev] ZCatalog caching with memcached

[Hedley Roos]

The usual Plone catalogs (portal_catalog, uid_catalog,
reference_catalog and membrane_tool) all run above 90% hit rate if the
server is up to it. portal_catalog is invalidated the most so it
fluctuates the most.

If the server is severely underpowered then catalogcache is much less
effective. portal_catalog hit rates will degrade over time. This is
the situation I'm currently facing with on one site, but more servers
will fix that.

It's quite easy to benchmark / load test with funkload. What I've
found is that memcached is very light on CPU, but if the Zope
processes are constantly using all CPU it is starved and runs into
trouble. As long as you avoid that case (which would be fatal without
catalogcache in any case) then everything works perfectly.

Run a few tests and let me know please.

Hedley