On the NetTuts.com site there's a new tutorial showing you how to introduce the Memcached tool to your application - a quick and easy way to cache data and optimize performance.

Your latest PHP/MySQL website is finally online. And it's awesome. But it's not as fast as you want it to be, because of the many SQL queries running every time a page is generated. And above that, you have the feeling it will not scale well under heavy loads. And you are most likely right. In this tutorial, we will see how you can greatly improve your website's responsiveness [...] by implementing a cache layer between your code and your database. The good news is it is fairly easy, and can be done in a few minutes!

They help you get the memcached server installed (a one-liner in most linux distributions) and how to install the memcached extension using PECL. Code is included showing you how to connect to the server, store data into the cache based on a generated key and how to pull the same data back out.

Maarten Balliauw has a new post to his blog with a guide to running mamcached on Windows Azure for PHP, a tool targeted towards PHP on Windows users to provide them with the ability to cache outside of their application.

While Windows Azure offers a distributed caching layer under the form of the Windows Azure Caching, that components currently lacks support for non-.NET technologies. I've heard there's work being done there, but that's not very interesting if you are building your app today. This blog post will show you how to modify a Windows Azure deployment to run and use Memcached in the easiest possible manner. Note: this post focuses on PHP but can also be used to setup Memcached on Windows Azure for NodeJS, Java, Ruby, Python...

He provides a phar-based scaffolding you can use to set up the instance and describes two ways of accomplishing it - the "short way" of relying on the scaffolding or the "long way" describing what the scaffolder does behind the scenes (complete with code). For this, you can also download the source and look through it.

On PHPBuilder.com today Jason Gilmore has written up a new tutorial about using memcached distributed caching for better performance in your web applications.

You probably know one of the easiest ways to improve performance is by caching all or parts of a page. But what might not be so obvious is exactly how this is accomplished. As it happens, a great solution called Memcached makes it trivial to incorporate caching into your website with great effect. In fact, relied upon by some of the largest websites in the world, among them Facebook, Twitter, Zynga, and YouTube, Memcached has essentially become the de facto website caching solution!

He walks you through installing the memcache extension for PHP (from PECL) and includes a bit of sample code that caches some fetched MySQL results to to the memcache server. With the extension installed you're just a few simple function calls away from better performance.

Andrew Johnstone came across an interesting problem when he tried to use memcached multigets with a large number of keys - it was throwing failures, but only when he tried it on Ubuntu.

I Spent a little while yesterday investigating why memcached causes problems with multigets returning results and ended up comparing debian vs ubuntu. [...] A larger number of keys than 200 causes memcached to fail to return valid responses, additionally the key length greatly varies the number items you can pull back within a single multiget on Ubuntu, Debian implementation of memcached is able to handle all requests regardless of key length size.

He includes the code for his brief test and the output of the test runs on both Ubuntu and Debian systems. They clearly show the failures on the Ubunut side, with it throwing errors about "memcached_oi_read" and a zero length value returned to recv().

On the Zend Developer Zone, Kevin has posted the latest episode of their ZendCon Sessions podcast series - Ilia Alshanetsky's talk about memcached.

Welcome to the ZendCon 2010 edition of the ZendCon Sessions. The ZendCon Sessions are live recordings of sessions that have been given at previous Zend Conferences. Combined with the slides, they can be the next best thing to having attended the conference itself. [...] This episode of The ZendCon Sessions was recorded live at ZendCon 2010 in Santa Clara, CA and features Ilia Alshanetsky giving his talk: "Memcached, the Better Memcache Interface"

You can listen to this latest episode in a few different ways - either through the in-page player, by downloading the mp3 or by subscribing to their feed. There's also slides if you'd like to follow along.

On Elijaa.org there's an interesting post (from back in May 2010) about using the "cas()" command in the memcached PECL extension to update the cached value of an object while preventing collisions with other scripts that might be updating the same value.

A series of commands is not atomic. If you issue a 'get' against an item, operate on the data, then wish to 'set' it back into memcached, you are not guaranteed to be the only process working on that value. In parallel, you could end up overwriting a value set by something else. [...] But PECL Memcached come with a useful function : cas().

The "cas()" function uses a checksum pulled out when the data is uplled using "get()". This token along with the updated data is passed into the "cas()" method that does the additional checking for you. A code snippet is included to show you its use.

On Developer.com today there's a new article talking about memcache and how you can implement it in your application to provide a performance boost for applications in a distributed environment.

As distributed system is part of the Memcached definition, you can install Memcached on various servers to make a larger caching server. In this way, Memcached helps reduce database loads to a minimum, resulting in faster and more responsive Web applications

They take some time to explain what memcache is - a simple to use caching system that reduces the dependency on other data sources - and how to get it installed (via the package manager of your choice). They suggest times on when and when not to use it as well as some of the security implications you'll need to worry about when implementing it. There's also a bit of sample code to help you get started in your application. You'll need the memcached extension to make it all work, though.

In a recent post to his blog Paul Reinheimer talks about a service (from WonderProxy) called Where's it Up? - a tool that can be used to see where in the world a site is up. He also outlines the technology behind it all.

The tool accepts a URL, and allows you to select global locations. It then attempts to connect to the given server and issue a HEAD request from the global locations you selected, and reports the results. [...] Building a reasonably robust application was trivial, thanks to being able to leverage the great technology built by others.

Tools that make up the application's stack include a Gearman server, curl, PHP with the pecl_http extension, memcached and supervisord. He details how they all fit together and why they built it in the first place.

In a new post to his blog Brian Moon takes a look at two of the memcache PHP libraries (memcache/memcached) and looks at some of the issues that might trip you up in using them.

Memcached is the de facto standard for caching in dynamic web sites. PHP is the one of the most widely used languages on the web. So, naturally there is lots of interest in using the two together. There are two choices for using memcached with PHP: PECL/memcache and PECL/memcached. Great names huh? But as of this writing there are issues with the two most popular Memcached libraries for PHP.

On the "memcache" side of things, he talks about the age of the code (not much recent development), a timeout-related parameter to the delete method and the 3.0 beta release that, in his words, "just needs to die". For the "memcached" extension things look a little brighter but there still hasn't been a stable release in over a year, at least not on the PECL side. The github repo, however, has seen quite a bit of change. The most major bug he found with this extension has to do with persistent connection leakage.

So, what should you do as a PHP developer? If you are deploying memcached today, I would use the 2.2.x branch of PECL/memcache. It is the most stable. Just avoid the delete bug. It is not as fast and does not have the features. But, it is very reliable for set, get, add.... the basics of memcached.

Alvaro Videla has submitted a new post from his blog today that looks at caching in PHP applications, specifically with APC or memcached.

Sometimes when talking with developers I see that there are some misconceptions regarding this two caching systems. That's why I'd like to share some concepts I've learned along the way.

Alvaro looks at both technologies and describes what they're good at and two of the main misconceptions about them - that APC doesn't mean caching data and that using memcached isn't faster than working with local values (you still have to make the TCP round trip).