[Plugin: W3 Total Cache] xCache Support

The reason is stability. Also on the operating systems tested, APC was faster (for WordPress) by a small percentage. Furthermore APC will be part of PHP6 making the need for other opcode cache’s quite a moot point.

APC leaves a lot to be desired such as a basic way to turn it off via .htaccess. I don’t need things I rarely use and get no traffic to (such as phpmyadmin or other tools that I only use) to be cached, ever. xCache easily gives you the ability to exclude these via a php flag in an .htaccess file.

I’m not sure what you mean by stability either. It’s just as stable as APC.

Mileage varies as do preferences, my comments are based on my research, experience and very large WordPress deployments. I’m not really interested in debates about opcode caches, use whatever you prefer.

Xcache is obviously now supported, but I thought I’d add some info. I have found that in my environment (Virtualmin on CentOS with Xcache, PHP running as user in FCGID), what works best is to use Xcache for the database and object cache, and disk for the minify and page cache.

This is because Xcache does not really support much administration (flush) except when running mod_php as user apache. I burned a lot of time trying to get it to work to run xcache for all caches, which is very very fast, but the need to constantly flush the page and minify caches was difficult, especially when lots of admin area users are involved.

You won’t see the FCGID processes in the Xcache admin pages, but believe me the database and object stuff does get cached although it does not show up. I have similar experience with Joomla in the same environment and xcache does indeed cache the db queries and objects.

@playgod

Agreed except that I have found better performance using Xcache for minify over disk.

I am running PHP as Apache (DSO) with disk enhanced for page caching and Xcache for minify, database and object and getting fantastic results.

c3m, Yes Xcache is fully functional only if you run PHP as apache. I haven’t found a way to get w3tc’s admin tasks (empty cache) to work running FCGID, that’s why I’m running minify via disk. I have xcache-admin setup properly and can access the admin, but w3tc’s login prompt does not work — on my server xcache requires https to log into the xcache admin; perhaps if I can modify the plugin to run the empty requests as https, it will work.

I do run other sites on my server as apache with mod_php, however the tradeoffs in convenience and security are not worth it with WordPress, IMO — having to change permissions on upload directories for auto-updates and installs is a hassle.

I’m thinking of removing Xcache and installing APC instead, since it will likely be better supported.

Nonetheless, I am very impressed by the performance gains and ease of use with this plugin. Here’s hoping switching to APC will solve my admin issues and allow me to cache more in memory vs disk.

APC and Xcache have proven to be pretty comparable in terms of benchmarking, sometimes with Xcache beating APC, but it proves to be more unstable than APC, so results may fluctuate here and there. APC is the best alternative as Frederick said… due to PHP6 support. However, Ive been seeing that APC and specific modules like suphp can actually cause a decrease in performance. a better setup would be using php-fpm or php-fcgi with APC.

I have xcache-admin setup properly and can access the admin, but w3tc’s login prompt does not work

That’s not what’s happening. When admin password for xcache cache is empty, there will be a prompt when trying to empty cache. That’s how xcache works, it has nothing to do with W3TC.

Thanks braddor, I’ve since switched to APC for my server and all is running well.

Frederick, APC is working better than xcache. Thanks for this plugin!

Welcome.

very useful topic! thanks all!

my wordpress blog has 8k visitors/day, 100-200 online at the same time

after reading this topic, i uninstall xcache and install APC

so now i need to change all from xcache to apc right, is it better?

If you have a single server, use disk enhanced for page cache, disk for minify and you can try APC for object cache and database cache and see if those improve performance for your case.

I found W3 Total Cache asking me for the xcache Administration password, too, but even if I entered it correctly, it was not accepted. Most odd.
It did seem related to minify and page cache too. I have not isolated it yet, though.

I’m using CGI as the PHP Handler (not DSO, not FCGI); I think this is part of the problem. I can’t clear the W3 Total Cache, because xcache administration wants me to authenticate, and when I put in the credentials, it doesn’t seem to make any difference.

@gravitydk The xcache admin username and password are required for W3 to clear the cache. Make sure you are using a md5 hash string for your password in the xcache.ini.

@c3mdigital is correct, this has nothing to do with W3TC itself actually. BTW, I think there is a directive to disable the need for administrative authentication for xcache.