Memcached Debuging/Server Logs Monitor the Memcached Servers?

Question

I have chat engine which is based on the Memcached variables, putting them into arrays and reading them in other end via jquery,

which works fine 95% of the times, however when the server load is high memcached (presume its the memcached) the crash and browser gets stucks up.

I dont think its jquery issue since this only happens when the server load is very high.

I need a way to monitor the memcached servers or somehow write a log file into where the fails/errors comes in...

Any idea on how i can do this ? or any idea why memcached servers fails ? I run the memcached as follows

$GLOBALS['MemCached'] = FALSE; $GLOBALS['MemCached'] = new Memcache; $GLOBALS['MemCached']->pconnect('localhost', 11211); 

My memcached config is as follows

#! /bin/sh # # chkconfig: - 55 45 # description: The memcached daemon is a network memory cache service. # processname: memcached # config: /etc/sysconfig/memcached # pidfile: /var/run/memcached/memcached.pid # Standard LSB functions #. /lib/lsb/init-functions # Source function library. . /etc/init.d/functions PORT=11211 USER=memcached MAXCONN=1024 CACHESIZE=128 OPTIONS="" if [ -f /etc/sysconfig/memcached ];then . /etc/sysconfig/memcached fi # Check that networking is up. . /etc/sysconfig/network if [ "$NETWORKING" = "no" ] then exit 0 fi RETVAL=0 prog="memcached" pidfile=${PIDFILE-/var/run/memcached/memcached.pid} lockfile=${LOCKFILE-/var/lock/subsys/memcached} start () { echo -n $"Starting $prog: " # Ensure that /var/run/memcached has proper permissions if [ "`stat -c %U /var/run/memcached`" != "$USER" ]; then chown $USER /var/run/memcached fi daemon --pidfile ${pidfile} memcached -d -p $PORT -u $USER -m $CACHESIZE -c $MAXCONN -P ${pidfile} $OPTIONS RETVAL=$? echo [ $RETVAL -eq 0 ] && touch ${lockfile} } stop () { echo -n $"Stopping $prog: " killproc -p ${pidfile} /usr/bin/memcached RETVAL=$? echo if [ $RETVAL -eq 0 ] ; then rm -f ${lockfile} ${pidfile} fi } restart () { stop start } # See how we were called. case "$1" in start) start ;; stop) stop ;; status) status -p ${pidfile} memcached RETVAL=$? ;; restart|reload|force-reload) restart ;; condrestart|try-restart) [ -f ${lockfile} ] && restart || : ;; *) echo $"Usage: $0 {start|stop|status|restart|reload|force-reload|condrestart|try-restart}" RETVAL=2 ;; esac exit $RETVAL 

Answer 1

Define an additional variable in /etc/sysconfig/memcached:

PORT="11211" USER="memcached" MAXCONN="1024" CACHESIZE="64" LOGFILE="/var/log/memcached.log" OPTIONS="" 

Edit the start() function in the init script as belows:

start () { #echo -n $"Starting $prog: " # insure that /var/run/memcached has proper permissions if [ "`stat -c %U /var/run/memcached`" != "$USER" ]; then chown $USER /var/run/memcached fi #daemon --pidfile /var/run/memcached/memcached.pid memcached -d -p $PORT -u $USER -m $CACHESIZE -c $MAXCONN -P /var/run/memcached/memcached.pid $OPTIONS -vv > $LOGFILE 2>&1 $prog -d -p $PORT -u $USER -m $CACHESIZE -c $MAXCONN -P /var/run/memcached/memcached.pid $OPTIONS -vv > $LOGFILE 2>&1 RETVAL=$? #echo [ $RETVAL -eq 0 ] && action $"Starting $prog: " /bin/true && touch /var/lock/subsys/memcached } 

then restart the memcached, you'll see something like this in the /var/log/memcached.log:

slab class 40: chunk size 616944 perslab 1 slab class 41: chunk size 771184 perslab 1 slab class 42: chunk size 1048576 perslab 1 <26 server listening (auto-negotiate) <27 server listening (auto-negotiate) <28 send buffer was 129024, now 268435456 <29 send buffer was 129024, now 268435456 <28 server listening (udp) <29 server listening (udp) 

Don't forget to configure logrotate.

Answer 2

First, you are not showing memcached configuration, you are showing the startup script. You need to look for a file named like /etc/memcached.conf. To enable logging, you need to uncomment the line

logfile /var/log/memcached.log 

Also, you can increase the verbosity by enabling -v or -vv option.

If memcached is crashed, you can look into system logs /var/log/messages and /var/log/syslog to check for possible error conditions.

Answer 3

Considering your memcached config is at [/etc/sysconfig/memcached] (Redhat RHEL & Centos 8 etc) you can just add the following switch to your options and restart memcached. Then it will log stuff into /var/log/messages(add rotation if you like later)

OPTIONS="-vv" 

If you don't want too much logging remove one of the v

The following configuration will make memcache listen on localhost and disable udp in addition to logging to /var/log/messages

OPTIONS="-l 127.0.0.1, -U 0, -vv" 

After you're satisfied with logging and you don't need logging anymore, just remove everything from options [OPTIONS=""] then use the following commands to check when you need to:

memcached-tool 127.0.0.1:11211 stats 

OR

echo stats | nc 127.0.0.1 11211