[horde] Horde Implementation Going South

[Dave Cunningham]

Hello fellow Horde users,

My company recently implemented Horde and IMP for our webmail system.  Everything initially seemed fine until the usage really ramped up.  We are now approaching 2000 active sessions on our servers and things are quickly going south.  Any suggestions for performance improvements are greatly appreciated.

Here are the specs:

(turba) H3 (2.1.4)
(trean) 1.0-cvs
(kronolith) H3 (2.1.6-cvs)
(gollem) H3 (1.0.4-cvs)
(ingo) H3 (1.1.3)
(agora) 1.0-cvs
(imp) H3 (4.1.4)
(horde) 3.1.4
(mnemo) H3 (2.1.1)
(passwd) H3 (3.0.1)
(nag) H3 (2.1.3)

Dual Core Xeon 2.66Ghz 1066FSB - 8GB

Redhat EL4 x86_64
Zend Optimizer
Apache Server version: Apache/2.0.52
 Server built:   Jun 29 2007 05:08:11
 Server's Module Magic Number: 20020903:9
 Architecture:   64-bit
 Server compiled with....
 -D APACHE_MPM_DIR="server/mpm/prefork"
 -D APR_HAS_SENDFILE
 -D APR_HAS_MMAP
 -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
 -D APR_USE_SYSVSEM_SERIALIZE
 -D APR_USE_PTHREAD_SERIALIZE
 -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
 -D APR_HAS_OTHER_CHILD
 -D AP_HAVE_RELIABLE_PIPED_LOGS
 -D HTTPD_ROOT="/etc/httpd"
 -D SUEXEC_BIN="/usr/sbin/suexec"
 -D DEFAULT_PIDLOG="logs/httpd.pid"
 -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
 -D DEFAULT_LOCKFILE="logs/accept.lock"
 -D DEFAULT_ERRORLOG="logs/error_log"
 -D AP_TYPES_CONFIG_FILE="conf/mime.types"
 -D SERVER_CONFIG_FILE="conf/httpd.conf"
mysql  Ver 14.12 Distrib 5.0.45, for unknown-linux-gnu (x86_64) using readline 5.0
PHP 4.3.9 (cgi) (built: May  4 2007 11:04:51)
 Copyright (c) 1997-2004 The PHP Group
 Zend Engine v1.3.0, Copyright (c) 1998-2004 Zend Technologies
    with Zend Extension Manager v1.2.0, Copyright (c) 2003-2006, by Zend Technologies
    with Zend Optimizer v3.2.8, Copyright (c) 1998-2007, by Zend Technologies
    with jobqueue_client wrapper v1.0, Copyright (c) 2004-2007, by Zend Technologies
    with <b>DISABLED</b> Zend Download Server v1.0.6, Copyright (c) 2003-2005, by Zend Technologies
    with <b>DISABLED</b> Zend Platform v3.0.3, Copyright (c) 1999-2007, by The Zend Platform presently supports only Apache, ISAPI and FastCGI SAPIs
    with Zend Debugger v5.2.8, Copyright (c) 1999-2007, by Zend Technologies



The major problems:

1.) Sometimes a single Apache process quickly builds up and eats 30, 40 or even 50% of the ram on the system.  Sometimes this process finishes.  Other times, especially if the overall system load is already high, it simply hangs and eventually brings down the entire web server.  I then have to kill and restart apache.  I have tried tweaking httpd, following the performance suggestions provided with the horde documentation.  Keepalives are on and the number of threads is high.

2.) MYSQL - We have mysql running on a separate server of the same specs.  It frequently uses 100% of BOTH cpus in what appears, by using myTop, to be a bunch of Join statements on the horde_datatree table. Switching to InnoDB seemed to make it faster at first.  But, as the number of sessions increased, all performance increases were lost and perhaps made worse.  I also tried upgrading mysql from the stock RHEL4 version 4 rpm to the V5 RPM from mysql.org.  There was no noticeable difference there.

Any suggestions would be greatly appreciated.

Regards,

Dave Cunningham
Systems Administrator
MECnet