Connection Pooling using MySqlConnection
This MySQL Connector/Net connection string can be used for connections to MySQL.
From version 6.2 idle connections are removed from the pool, freeing resources on the client (sockets) and the server (sockets and threads). Do not manually keep (global) connections and open close. Keep connection object creation and disposal as tight as possible, this might be counterintuitive but pooling mechanisms will take care of caching well and your code will be cleaner.
This is the default behaviour.