just curious - openldap-technical

21 Apr 2009


      Hello, I've been trying past weeks upgrading my production openldap 
software. I started from 2.4.11 when it was available, through all 
available versions, up to 2.4.16. I tried package builds, and my own 
builds. Each version except 2.4.10 was likely to hang, as it's production, 
and load is quite high, I haven't too much patience to debug and 
researching what's actually going on, but I tried disabling syncrepl (no 
effect), some different settings for bdb backend and slapd thread, 
concurrency etc ( starting from settings which caused no problems with 
2.4.10 ), and finally, got back to 2.4.10 which works fine. Between 
version change I noticed that 2.4.11+ is build with newer libdb versions 
(package depends), starting from libdb4.2 (2.4.10), up to libdb4.7 (newer 
openldap version). I didn't try to build 2.4.15+ with some old (4.2) 
libdb.
Is it some major significant jump between 2.4.10 and all later versions?
some general rewrite of some feature ? It's not syncrepl related, as 
daemon hang no matter whether configured as slave or standalone.
The symptoms was, it was (in general) producing BIGGER server load
than 2.4.10, and, although daemon process did not segfaults, server
stopped responding for requests (?). With higher load I wasn't able
to try logging and use of debug symbols.
I expected it will work without any slapd.conf, anyway nor leaving it
untouched, nor some minor reasonable changes had no effect.
So, what's going on? :) Is it possibly related to libdb ? or what? 
What else could it be ? Except libdb ( 5 different versions available
in my system with one default, usually newest ), there was no other
software change, just upgrading openldap/libldap.
Any clues you may have? I'm sorry I cannot provide more information,
anyway config is rather standard and simple, some custom schemas
added with indexing, that's all. 2.4.10 has no problems at all,
and significantly lower general machine load. ( if 2.4.10 = 100%, 2.4.11+ 
makes 300-400% )
Actually I'm not expecting some miracle explanation, anyway it's 
interesting what could it be.. I have about 25 000 entries total in
my directory tree, it's used as NSS source, and other information
for various applications.
regards :)
P.