pool.end() does not return a proper promise

[Simo Pähk]

I encountered an issue in my software wherein connections would be left open, thus reaching the PostgreSQL connection limit for that user after a few runs.

My code basically did this:

1. open a VPN connection;
2. connect to a database, fetch data;
3. terminate the pool (wait for the returned promise);
4. close the VPN connection.

As it turned out, pg-pool was unable to properly terminate idle connections, because the VPN tunnel was closed before necessary signals could be sent. I could solve the issue by waiting an extra second between points 3) and 4), so I suspect the issue lies on these lines: 91 and 135. Namely, client.end() returns a promise that resolves only once it receives the 'end' signal, but this promise is not forwarded to _pulseQueue(), which reports the pool as properly closed as soon as it simply requests the closing of all idle connections.