Reintroduce connection pool timeout

Initial description

When a connection is defuncted, new connections to that host cannot be created until the reconnection interval defined by the reconnection policy is elapsed.

If, in the meanwhile, an attempt is made to borrow a connection from that host, the pool will return a connection future that will never complete.

The following snippet reproduces the error:

Final Resolution

A pool timeout has been reintroduced. This timeout is configurable via PoolingOptions.setPoolTimeoutMillis(int).