race condition?

I am running freeradius 1.0.5 version. I know this is old. ldap is used in authorization and pap is usually used in authentication. We made a client tool which can send 1000 packets per second (from data file) to freeradius. What we noticed that in multi-thread, there was a race condition which makes some ldapsearch failures. We are positive in that there is no problem in our ldap because we already tested our ldaps with a similar tool and verified that our ldap can support much more load. Do you have any idea what part of things that I need to check or was there any update in ldap with this kind of issue? Kevin