In the general case, there is no way to list all the keys that a memcached instance is storing. You can, however, list something like the first 1Meg of keys, which is usually enough during development. Here’s how:
Telnet to your server:
telnet 127.0.0.1 11211
List the items, to get the slab ids:
stats items
STAT items:3:number 1
STAT items:3:age 498
STAT items:22:number 1
STAT items:22:age 498
END
The first number after ‘items’ is the slab id. Request a cache dump for each slab id, with a limit for the max number of keys to dump:
stats cachedump 3 100
ITEM views.decorators.cache.cache_header..cc7d9 [6 b; 1256056128 s]
END
stats cachedump 22 100
ITEM views.decorators.cache.cache_page..8427e [7736 b; 1256056128 s]
END
Thanks to Boris Partensky in the Memcached group here
There you go!