Re: RE24 (2.4.15) slapd consuming large amounts of CPU

[Howard Chu <hyc@symas.com>]

John Morrissey wrote:
> I upgraded one of our consumers to 2.4.15 recently, from RE24 as of
> 20090113. Its configuration stayed the same, save for bumping the BDB cache
> size from 256MB to 2GB.
>
> After a few hours of uptime, slapd suddenly begins consuming enormous
> amounts of CPU (a three- to four-fold increase over less than a few minutes,
> and is sustained until slapd is restarted).
>
> A backtrace (below) shows many threads waiting on a mutex in bdb_cache_*().
>
> This is with BDB 4.7 (with all patches applied) on Debian lenny.
> 'db_stat -c' output is below (and looks sane), in case that's useful.
> Thinking thread contention, I bumped the worker thread count (slapd.conf
> threads directive) down from 32 to 8, which has made no difference.

From the trace it looks similar to ITS#5860. The patches for this are in 
HEAD, not yet released.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/