Related to https://issues.apache.org/jira/browse/QPID-4853
Often, when a connection is cleanly closed, the connection-close handshake completes but the connector is never closed. All that is needed is for one more connector_process cycle, but the connector never again appears in the work list.
There is an optimization in the connector processor that says "if the socket has accepted all of the current data for send, clear the SEL_WR flag". The problem is that when the data-for-send is the last data to be sent on the connection, the connector is never again processed and hangs, using resources and keeping the socket from fully closing.