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.