based on the timestamp in the ldap.log, it is about 10-15 minutes older than current time. 
I see a lot of ABANDON msgs which i suspect that there are way too many queries (not ldap connection itself) in a connection. Also, the log shows the constant logs of follwing as well:

connection_input: conn=321629 deferring operation: pending operations
connection_input: conn=318818 deferring operation: too many executing

Looking thru the archive that this is an issue on the client side, and I believe that's true based on the ABANDON msgs on long lasted session ids. 

I was using logging set to stats, sync .  I have changed to none and the symptom of lagging of log timestamp has disappeared and queries are working properly again. 

My question is, is there a way to safely log stats without hampering performance to the point queries are not returing at all ? 

I am using openldap-2.4.39 ( yes i should upgrade soon :( )