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Re: thread problem OpenLDAP 2.1.8 + Solaris 9

At 09:41 AM 2002-11-26, Quanah Gibson-Mount wrote:
>Kurt,

I note that addressing posts to an individual will often result in your
post not being responded to by others on this list...

>Having now done much tweaking with openldap, we are now up to a dismal average of 14 queries/second with 20 hosts over a 74.5 minute period.

>I am fairly positive we are indexing everything necessary.  All we are doing right now is filtering on suseassunetid to find the sumaildrop attribute.  Both of those attributes are indexed, as are objectClass, entry, uid, dc, and cn.  Example query: ldapsearch -h <host> -b"cn=accounts,dc=stanford,dc=edu" suseassunetid=quanah sumaildrop

I note that a query like this is actually quite complex... and includes
all the TCP establishment, maybe DNS reverse lookups, SASL authentication
and security layer establishment, identity mapping (possible with search
indirection), ....   That is, a lot more than a single LDAP search operation.

>A few things we have noticed:
>
>One:  slapd spends a lot of time determining the ACL's for attributes, every single time a query is made, instead of caching the ACL's.  I am interested in its #1523, but do not have access to the patches.  Would it be possible to send them to me, so I can see if that improves our performance any?

Seems the patch was uploaded under a different name.  I've added a symlink
to the repository so that URL in the ITS now works.

>Two:  slapd will be very responsive and quick in its answers for a period of time, then will just hang for several seconds, or greatly slow down the rate at which it is returning queries.  It will then pick up again, being quite responsive.

I would look at three areas were such can easily occur.  One, something in the
connection accept code (which is single threaded) hanging up on something...
like reverse DNS lookups.   Two, something in the lower-level authentication
framework (SASL,GSSAPI,Kerberos) hanging things up.  Three, contention for DB
pages (if using back-bdb) or the LDBM giant r/w lock (if using back-ldbm).

Kurt