(ITS#3850) OpenLDAP 2.2.26-sasl hang after "defferring operation: binding"

[beck@ualberta.ca]

Full_Name: Bob Beck
Version: 2.2.26
OS: OpenBSD 3.7 (i386)
URL: http://bofh.cns.ualberta.ca/openldap
Submission from: (NULL) (129.128.11.43)


I'm running openldap 2.2.26 with sasl installed from the OpenBSD ports tree, 
OpenLDAP can be made to stop accepting binds (or any new connections) by
repeated rapid bind attempts. We have successfully replicated this in two ways:
1) by having 20 users in a room attempt to log in to a system and use it.
2) by running a couple of programs that attempt to repeatedly bind for
authentication.

The symptom seen in the logs is that stuff works fine until a bind is deferred.
After this point, *all* future bind attempts are deferred, and no connections
appear
to ever be closed. i.e.
Jul  6 10:54:17 ldapauth2 slapd[8106]: connection_input: conn=887 deferring
oper
ation: binding

It appears that once a bind operation is deferred, nothing ever reschedules it
to complete, and all future attempts hang. In the end when you forcibly kill
the
server the blocked threads finally attempt to exit.

A level 15 debug log from the problem being produced is available at
http://bofh.cns.ualberta.ca/openldap
as well as the slapd.conf from the machine.