When sending large messages loss of connection is not detected even with heartbeats enabled

E.g run qpid-send --broker <remote-broker> --connection-options

--messages 0 --content-size 1600 --report-every 1000 --address amq.topic

then after some time pull the network cable (you have to do this, a kill -STOP on the broker is not sufficient). The test will continue sending messages then eventually hang (when buffers are full). If you reconnect the cable, the connection will fail but if you don't, it will not.

If you reduce the size e.g. to 100 bytes , the connection fails as expected after two heartbeat intervals (16 secs in this case).