[Zope] Zope Performance with Multiple Mount Points

[Brian Brinegar]

We've recently moved to a Zope configuration with approximately 30
separate databases mounted at mount points within a main database.

Previously, we ran a single database which was approaching 300GB in
size. We chose to split the database to reduce Data.fs size. We now run
30 separate ZEO Servers (on a single machine).

However, after switching to this configuration we've noticed some
performance issues.

Initially, after a client is restarted and builds out it's caches the
site runs very quickly. However as the memory usage grows the
performance degrades. If the client gets into swap the client
practically dies.

We had 10,000 object caches on each of the databases with 2 threads on
the client. 30 x 10,000 x 2 = 600,000 objects in memory. We've since
reduced the cache sizes to 1,000 or 30 x 1,000 x 2 = 60,000 objects.
This seemed to extend the life of a client between restarts.

Generally, our client machines will hover around 97%-99% memory usage
and 90%-100% CPU (on a 2 CPU machine).

We still experience periodic performance problems and are looking for
any input that might help us address them.

Thanks for your input,

-- 
Brian Brinegar
Web Services Coordinator
Engineering Computer Network