Memcached plugin masks setting changes on multisite installs

[kiloman]

I'm using WP 3.0.1 in a multisite configuration with the Wordpress memcached plugin version 2.0.1 from svn trunk. memcached version is 1.4.5. I'm also using HyperDB to split reads and writes between remote master and local slave MySQL instances.

When the memcached plugin is enabled, I am unable to effect changes within the administrative interface. I don't have an exhaustive list, but things I've noticed include editing user profiles, adding post categories, editing posts, etc. The changes make it to the database, but the new values are not displayed in the web interface.

If I restart or flush memcached, I can see any changes I've made, but any new ones are masked. If I uninstall the plugin or shut down
memcached, everything works fine.

[ryan]

user_meta needs to be added to global groups. That could explain profile staleness.

[ryan]

(In [15482]) Add user_meta to global groups. see #14475

[kiloman]

Tested the patch against 3.0.1. Same issue. Note that it's not just user profile that's getting cached, but also the list of available tags, categories, etc.

[markjaquith]

No movement on this recently. Punting.

[scribu]

Probably related: #14992