Comment 8 for bug 1581133

This doc is a bit outdated. memcache_pool was a workaround in it's time of eventlet and currently there are replacement recommendations: pylibmc, pymemcached.
For our tasks simple memcache client is the optimal solution as memcache_pool has some performance issues with our current multithreading/non-eventlet model.
Another thing is that Fernet tokens do not require storage anymore, so memcached is used just for caching right now and not for token storage anymore.

Information about tokens in use you can find in keystone.conf [token]provider parameter. You can find `driver` nearby that can confuse you, but if provider is set to fernet, driver is not used.