> I'm not sure that it's the most efficient way to close the transport. It may be better to close the transport in the connection_lost() method of the protocol.

"process_exited", not "connection_lost".

I implemented this option which is simpler and more efficient (always and immediatly close the transport).

Clearing the reference to the transport in the Process is less important, it can be done later in a different issue/changeset. I close this issue.