Re: slapd problems under stress

["Kurt D. Zeilenga" <Kurt@OpenLDAP.org>]

At 05:52 PM 6/29/00 +0200, Christian Lorenz wrote:
>Hi *!
>
>I have integrated two backends into slapd and we are now
>observing problems with slapd if it got under stress:
>
>Our test program (written by using libldap) starts 80 async
>request and waits for their results. This is done every
>10 seconds. In case of a time-out (10 seconds) all pending
>operations will be abandoned. Sometimes the slapd crashes
>with a SEGV, sometimes it hangs, sometimes it aborts (from
>assert() during a memory allocation)!

These sound like resource exhaustion errors.  OpenLDAP
does not deal with such very well.  You need to configure
the server such that you don't exhaust resources.  Given
the test you are doing, you likely are exhausting process
space or stack space or heap space.

>After that, we concentrated on a single backend which I
>stripped down so that the search does nothing but a
>'send_ldap_result(conn,op,LDAP_NO_SUCH_OBJECT,NULL,NULL,NULL,0);'.
>Same problems!
>
>The next step was to use the 'standard' ldbm backend.
>And again: we have the same problems!
>
>We are running linux 2.2.14, OpenLDAP 2.0-devel (last
>update from the CVS: 28 June 2000), debug level for all
>tests was 255.
>
>I think that the problems are thread related.
>Are there any known problems? Is it possible to set a limit
>on the number of concurrent threads?

We don't have knobs (yet) to control this.