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Using memcache to store objects is not a new strategy to reduce database load and improve responsiveness of an application, but it is an often overlooked option due to the ‘extra’ labor of installation and configuration. Hopefully the following information will make this easier for some and me to remember.

Installing and configuring a memcache server on linux:

1. Download, configure, and compile memcache.
   • wget http://memcached.org/
   • ./configure
   • sudo make && make install
2. Create a startup script:

   #! /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=2048
   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 ${pidfile} memcached
   RETVAL=$?
   echo
   if [ $RETVAL -eq 0 ] ; then
   rm -f ${lockfile} ${pidfile}
   fi
   }
   # restart
   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
   

3. Add the daemon to the service manager, and enable it for runlevel3:
   • chkconfig –add –level 3 memcached
4. Start the Memcache server:
   • service memcached start

You should now have a functioning memcache server, available on the localhost, port 11211. you can check to see if it’s running with service memcached status. Now, to use it within PHP for example you have to provide the PHP extension for memcache so that you can store and retrieve data.  For this purpose, there is a PECL extension available here: http://pecl.php.net/package/memcache

Building the extension is fairly easy:

1. wget http://pecl.php.net/get/memcache-3.0.8.tgz
2. tar -xvzf memcache-3.0.8.tgz
3. cd memcache-3.0.8
4. phpize
5. ./configure && make && make install
6. Check /etc/php.d/memcached.ini, if it doesn’t exist or correctly point to the compiled extension (*.so) PHP will not be able to communicate with the memcache server.

Now the easy part -> using it. For that, RTFM. http://php.net/manual/en/book.memcache.php