[Zope-dev] ZEO cache instrumentation -- any takers?

[Leonardo Rochael Almeida]

On Wed, 2002-10-02 at 16:14, Guido van Rossum wrote:
> A while ago I announced a new ZEO cache instrumentation feature, and
> asked if anyone was interested in enabling this instrumentation in
> their site.  I got exactly zero responses... :-(
>=20
> I'd like to repeat the offer.

We (Hiperl=F3gica) have some ZEO installations:

* A single ZEO client with UNIX socket that was used because Zope used
to crash a lot before Python 2.1.3 and restarting was way faster with
ZEO (hi Matt!). This one is in production w/ 75k hits/day.

* A single ZEO client with a ZEO server in a different machine, both
Win2k (the client intends to add more ZEO clients and a load balancer
(eventually) but insisted on testing this otherwise meaningless
configuration)

* Two identical Win2k machines running a ZEO client and a ZEO server
each. Both ZEO clients connect to the ZEO server on the first machine,
but the ZEO server on the second machine is there for manual failover.

Following Guido's suggestion, we will be installing that instrumentation
in all of those sites but since we're talking about ZEO, lemme ask for
some help:

The last two installations belong to the same client, and are both
experiencing a problem that I believe is related to ZEO latency. Both
sites depend heavily on a single ZCatalog for operation (one ZCatalog
hit in almost every page, with some pages with more than one ZCatalog
hit). When site content is being managed, we're hitting ReadConflict
errors (They read like this: ZODB.POSException.ReadConflictError on
database read conflict error (oid000000000004c0a4, class
BTrees.OOBTree.OOBucket)). The reference to BTrees makes me think this
is ZCatalog related, we don't use BTrees ourselves anywhere else and we
only use regular Folders as bases for our folderish objects, and
managing content causes the reindexing of objects. Which I think is what
is triggering the conflict errors.

You guys have any tips to avoid this or to help narrow this problem
down?

--=20
Ideas don't stay in some minds very long because they don't like
solitary confinement.