Adventures with WP-Cache2 & APC

Update 3: see update 2 for the solution!

APC (Alternative PHP Cache) is great for WordPress. It caches the compiled WordPress PHP files and greatly speeds up subsequent loads. I even wrote a WordPress plugin to make WordPress store its objects in APC instead of in the default file-based object cache.

WP-Cache2 is also great for WordPress, because it caches the HTML output of WordPress for a specified period.

So if both are good, together they should be awesome, right? Well… in theory, yes. Unfortunately, I’ve been having a heck of a time getting them to play together. What would happen was that pages would start showing up blank. Just a white page. Real helpful. The same thing happened when you tried to access /wp-admin/ The only way to fix it was to delete WP-Cache2. In desperation, I removed all the error-silencing @ from WP-Cache2. Ah. It was some problem with class_exists() and APC. Apparently, APC doesn’t play well with class_exists().

Here is the solution I came up with… it seems to be working. I’ve been able to enable/disable WP-Cache2, restart Apache2, flush APC, with no White Page of Death so far!

[ I have removed my solution, to keep from misleading people, as it gave me problems later on ]

Restart Apache, flush your WP-Cache2 cache, and cross your fingers. I’ll update if I have any problems with this.

Update: Well that was short-lived! I’m still looking for a solution. It may involve naming the wp-cache-config.php file differently for each WP install that is running WP-Cache2.

Update 2 (SOLUTION): This seems promising. In php.ini in the [apc] section I set apc.filters = wp-cache-config which should exclude wp-cache-config.php and wp-cache-config-sample.php from being cached by APC.

Update 3: Yep! That did it!