Yes, we can share a single instance of Memcache between multiple projects because being a memory storage space, Memcache can be run on one or more servers. In Memcache, you can also configure your client to speak to a particular set of instances.
We can also run two different Memcache processes on the same host being completely independent and without any interference. If you partition your data, it is important to know from which instance to get the data from or to put into.
