Hi there
I know that this is not an issue specific to Percona. But we are using the Percona binaries and I’m sure that I can find competent people here 
FEDERATE engine opens a lot of sessions, over which I would like to have some control.
These sessions seem to be closed only when the FEDERATED tables are flushed. Our issue is that all these connections consume a lot of threads on the master server, but actually are in sleep state most of the time.
Unfortunately the most obvious approach to solve this does not work: FEDERATED does not cope well when the connections are closed from the remote side. Hence flushing seem to be the only solution.
I would like to write some sort of script that flushes tables when they haven’t been used for a certain time. But till now I couldn’t find any meaningful information to decide which tables to flush to release unused resources.
Any hint will be greatly appreciated!
Cheers,
Till