Memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.
Memcached on Ubuntu has two components. A standalone program running on your server and a client PHP extension.
To install memcached, run the following command:
sudo aptitude install memcached php5-memcache php-pear ..... Creating config file /etc/php5/conf.d/memcache.ini with new version
sudo aptitude install php5-dev libmemcached-dev sudo pecl install Memcache ..... Installing '/usr/lib/php5/20090626+lfs/memcache.so'
Please choose
Enable memcache session handler support? [yes] : yes
Find your php.ini file and execute following command
php -i | grep php.ini nano /etc/php5/apache2/php.ini
Add the line to the bottom of the file: memcache.hash_strategy=”consistent”
memcached -d -m 1024 -l 127.0.0.1 -p 11211
If you get a message saying, “can’t run as root without -u switch” then try this:
memcached -d -u www-data -m 1024 -l 127.0.0.1 -p 11211
To active new configuration execute following command
/etc/init.d/apache2 restart /etc/init.d/memcached restart
Verify memcached
pgrep -fl memcached netstat -an | grep 11211
Check memcached status
memcached -u www-data -vv ps -A | grep memcached
There are either procedural, or object oriented functions already available. Here is an example of a script which will store a simple variable and then retrieve it and display it.
/* procedural API */
if (class_exists('Memcache')) {
$memcache = new Memcache;
try {
/* connect to memcached server */
$memcache_obj = memcache_connect('localhost', 11211);
} catch (Exception $e) { print_r($e);}
if ($memcache_obj) {
/*set value of item with key 'var_key' using 0 as flag value,
* compression is not used expire time is 30 seconds*/
memcache_set($memcache_obj, 'var_key', 'some variable', 0, 30);
echo memcache_get($memcache_obj, 'var_key');
}
}
I’d recommend downloading memcache.php which is a php script showing you a lot of useful information about your memcached servers. Once downloaded, put it in a web facing directory on your server, and modify the $MEMCACHE_SERVERS array with your server addresses.