[Twisted-Python] connectionLost never reached after calling loseConnection: stuck in CLOSE_WAIT forever

[Stefano Debenedetti]

Hi,

I have a similar problem as described in this old mail [1] except
that I am not using threads at all.

Basically my app is a server that accepts connections from a client
(connection A), when A is established it opens connections B and C
to another server and forwards data from A to B and from C back to A.

Here is how data is forwarded:

def forward(_from, to):
    _from.dataReceived = to.transport.write
    to.transport.registerProducer(_from.transport, True)

def loseConnection(proto, onlost=lambda *args: None):
    proto.connectionLost = onlost
    proto.transport.unregisterProducer()
    proto.transport.loseConnection()

as soon as connectionMade has been called on connection A, B and C:

forward(A_protocol, B_protocol)
forward(C_protocol, A_protocol)

as soon as it decides its job is done and wants to tear down all
connections:

loseConnection(B_protocol)
loseConnection(C_protocol, lambda *a: loseConnection(A_protocol))