Cache defence

Posted on March 23, 2007
Filed Under plugins, techniques |

One of the criticisms WordPress is often on the receiving end of is that it performs poorly under load. By load we mean a Digging. And it’s true - most WordPress sites will collapse pretty quickly under pressure of a lot of concurrent traffic.

defense.jpgI think 90% of the problem is in the repeat visits to your mySQL database for most page displays. Certainly on most of the installs that have collapsed on me this has been the problem.

The simplest thing to do is install some caching software. The most common is wp-cache-2. I’ve just installed it here to test. Wordpress 2.0 onward come with inbuilt cache but there is some debate over whether this is quite up to scratch as yet; see http://www.thinklemon.com/weblog/2006/01/15/wordpress-20-cache-is-broken/ and http://www.webmaster404.com/optimizing-wordpress-cache

There is a fair amount of ambiguity. Once I’ve completed the test on the plugin and native I’ll report back here.

Any comments / experiences would be greatly appreciated though, especially if you are willing / able to provide any numbers on pageviews before and after setup. Sign derived from a photo by .

Comments

3 Responses to “Cache defence”

  1. Ray on March 30th, 2007 10:10 pm

    3 questions/comments:
    1) How did you find my post about it?
    2) Why are you referring to non-standardly? I would assume you’d get to it via
    http://raybdbomb.com/p/wordpress-performs-poorly.html
    not
    http://raybdbomb.com/index.php?name=wordpress-performs-poorly&page=
    3) I would go so far as to say that the mysql trips are 95%+ of the issue. My research has shown that a caching algorithm that triples or quadruples the CPU cycles but stays off of the database can handle 20 or more times the load as one that even connects to the database, but doesn’t necessarily do any queries.

  2. admin on March 31st, 2007 2:01 pm

    Hi Ray
    I think the answer to both 1 and 2 is that technorati spits out some strange URLs from time to time.
    As to the speed of the install, I’ve run WP on a number of setups and I’d agree with your diagnosis that the mySQL connections are the problem. wp-cache deals with it though, so all is good unless you have very active sidebar content that the caching kills.

  3. Ray on April 2nd, 2007 4:06 pm

    I see. What did you search for on Technorati?

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