bdb bad performance again (really need help)

[Vadim Tarassov <vadim.tarassov@swissonline.ch>]

Hallo everybody,

It is mainly the same message, previously posted by other users (see for 
example

http://www.openldap.org/lists/openldap-software/200309/msg00389.html).

We could not find solution for this problem in the list, hence decided 
to inform the list about this problem again.

We observe very bad performance of LDAP server (2.1.8, 2.1.22, 2.1.23) 
under load test conditions. Performance stagnates very fast with 
increasing number of concurrent LDAP clients (well, just 8 of them kill 
LDAP server), and remains very bad even after load is removed. 
Restarting LDAP server does not bring anything positive. However using 
db_recover we can restore performance (similar to what has been reported 
by Peter Johnson).

Howard Chu suggested:

1) Read Berkeley tuning documents (tbd)

2) take results of db_stat -c and db_stat -m commands and compare them.

We did it and we are ready to do it again if anyone on the list will be 
ready to help us to solve this problem. However we have not observed 
anything particulary odd (from our dumb user's point of view) when 
looking on db_stat output before and after load test. db_stat did not 
show anything after db_recover has been applied.

Suggestion to modify DB_CONFIG file caused following feedback from Peter:
=======================================================================
I setup the DB_CONFIG file and it helps.  The fast query scripts still 
start
to slow down but not as soon as before.  Also the scripts with the one 
second
delays ran without problems for 14,000 queries where before the started
having problems at about 7000 queries.

	There must still be something wrong with the software since I still have to
use db_recover to get response time back up to normal after a slowdown.
========================================================================

We have not tried to make corresponding changes in the file as we trust 
observations of Mr. Johnson and his conclusion.

Is there anybody who can suggest something to figure out what went wrong?

Thanx a lot in advance, Vadim Tarassov.