Chris Withers wrote at 2006-6-20 07:31 +0100:
>But, there also seems to be (to my untrained eye) random periods of
>slowness from then onwards, again, without any apparent signs of excess
>load, memory usage or disk i/o.
>I'm somewhat flumoxed as to where to go from here on the debugging front...
I have seen such behaviour when we still used cosine ranking
(with TextIndexNG): it needs excessive amounts of data
and can flush all other objects from the caches.
We dropped cosine ranking and the behaviour disappeared.
An essential help for the analysis was an instrumentation
(in our private Zope/ZODB version) of the ZEOServerStub code
to log information about the fetched objects: their oid, their class, their
size and how long fetching took.
For more information about ZODB, see the ZODB Wiki:
ZODB-Dev mailing list - ZODB-Dev@zope.org