Full_Name: Cyril Grosjean
OS: Red Hat Enterprise Linux Server release 5.4 (Tikanga)
Submission from: (NULL) (184.108.40.206)
My OpenLDAP server freezes, after a few requests, and I can't understand why.
I have a few LDAP clients (ldapsearch, a custom Java app. and
ApacheDirectoryStudio), running from different systems, either locally on the
OpenLDAP server, or on another OpenLDAP server, or on a remote workstation, and
none manages to get an answer from OpenLDAP. The connection is established but
each client gets stuck waiting for any result.
We can reproduce the freeze, after a few requests coming from the custom Java
application. The problem doesn't occur if we don't use that application.
The last time, it occured only a few minutes after the OpenLDAP daemon was
restarted, under very low load.
I use OpenLDAP 2.4.26, over Red Hat Enterprise Linux Server release 5.4
(Tikanga), Kernel version 2.6.18-164.el5, amd64 architecture over VMWare.
I also use BDB 4.8.30, and OpenLDAP's been compiled with the following options:
./configure --prefix=/opt/openldap-2.4.26 --enable-dynamic=yes
--enable-dynlist=yes --enable-memberof=yes --enable-ppolicy=yes
I noticed only 60 to 70 established connections on port 389 (according to
netstat) when the freeze occurs.
The OpenLDAP server is set in syncrepl mirror mode replication, and the other
OpenLDAP server (only used as a hot stand-by) works fine (but doesn't receive
any load). However, one can reproduce the problem with replication disabled.
Looks like you have a thread blocked trying to modify a record, while all the
other writer threads are blocked waiting for that writer to complete. The
output of db_stat -CA would help to indicate why the writer is blocked.
It also looks like you've configured your replication with mirrormode and
delta-syncrepl. This combination is not yet supported in OpenLDAP, certainly
not in 2.4.26. It may be supported in 2.4.27, depending on how our ongoing
testing turns out.
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/