[wp-hackers] MySQL MEMORY worth using for an object cache?

[Matt Mullenweg]

Robert Deaton wrote:
> 4). Full page to disk caching does more harm than good on a server
> that is expecting a beating, especially one like digg or slashdot. The
> reason for this is that often times so many comments are posted that
> the server is constantly having to regenerate these pages and write
> them back to disk.

My experience has been the opposite. Make sure you have the latest 
wp-cache, a previous had a bug where it would invalidate the cache for 
spam comments and comments stuck in moderation. Perhaps turning 
moderation in the situation would help as well, but I've never run into 
that problem.

> I believe there's some smaller optimizations that still may help. I
> personally believe throwing all the files together into one giant
> include would likely help.

The only advantage to that over APC would be no stat calls to see if the 
file has changed. You can actually tell APC not to check if a file has 
changed, which means you have to restart it whenever you update a file, 
but we found that had little or no effect.

I think a far larger benefit would come from simply dividing WP's files 
up more so not everything is loaded for every request. A lot of 
functions are used only for the backend, or only for RSS, or only on 
non-RSS pages, and being smarter about what code we include I think can 
have a big impact. This is different from on-demand loading.

> WP-Cache could use a rewrite from the ground up as well, imho. I wish
> I had more time to take this project under, but perhaps I will anyways
> in the coming weeks, or once summer starts.

It would be great if it supported multiple backends, like WP's own 
cache. WP-cache + APC or memcache would be pretty potent.

-- 
Matt Mullenweg
  http://photomatt.net | http://wordpress.org
http://automattic.com | http://akismet.com