This is my short tutorial of how to set up, use and monitor memcached on a PHP web server.
My webserver is a CentOS 5 webserver with cPanel.
Setup memcached
1. Setup libevent
This is a library needed by memcached. Install it:
wget http://monkey.org/~provos/libevent-1.4.14b-stable.tar.gz tar zxvf libevent-1.4.14b-stable.tar.gz cd libevent-1.4.14b-stable ./configure make make install cd ..
2. Setup memcached
Get and install the latest memcached code:
wget http://memcached.org/latest tar -zxvf memcached-1.x.x.tar.gz cd memcached-1.x.x ./configure --with-lib-event=/usr/local/ make make install
3. Add the libevent library to the path
If you attempt to run memcache at this point you will probably get an error for missing the libevent library. Register it:
touch /etc/ld.so.conf.d/libevent-i386.conf echo "/usr/local/lib/" > /etc/ld.so.conf.d/libevent-i386.conf ldconfig
4. Test memcached
memcached -d -m 1024 -u root -l 127.0.0.1 -p 11211
This opens up memcached server with 1024MB of RAM on port 11211. (memcached -h for more on options)
Connect via telnet to make sure it’s up:
telnet localhost 11211
Ctrl-C to exit. Done.
Setup the PECL extension for PHP
1. Setup PECL memcached
pecl install memcached
Careful: Notice the “d” at the end. Pecl also hosts an extension called “memcache”. This is a different implementation. All the examples listed below use “memcached”.
Add this line to your php.ini:
extension = “memcache.so”
2. Test the installation
Create a new PHP file within your document root directory with the following contents:
<?php
$memcache = new Memcache;
// Connect
if(!$memcache->connect('localhost', 11211)) {
die('Could not connect to server');
}
// Set the cache
$memcache->set("test_hash", "It works, mate!", false, 400);
// Get the cache
if ($ret = $memcache->get("test_hash")) {
echo $ret;
}
else {
die('Could not retrieve data from memcached');
}
?>
Save it and point your browser to this file.
You should get: “It works, mate!”
For more information on how to use memcached, check out the memcached manual pages.
Further steps
Starting memcached as a service
Check out this tutorial by Danny Bembibre.
Monitoring memcached
This has given me some hard time.
There are all sorts of tools to monitor the cache, some are web-based, some are local applications. I’ve had tough luck finding something that I could recommend.
The only one I’m currently using is a top-like command line tool named: memcache-top.
To install and run it:
wget http://memcache-top.googlecode.com/files/memcache-top-v0.6 chmod +x memcache-top-v0.6 ./memcache-top-v0.6
That’s all. I hope this will be useful to all you out there.
If you have any comments please do not hesitate to contact me.
