Do not schedule requests to server if socket is in CLOSE_WAIT state

[EvgeniiMekhanik]

Sockets that are in the CLOSE_WAIT state are waiting for an acknowledgement from the client (PC) end of the connection so that the socket can be closed completely. They will wait FOREVER, there is no timeout value.

Problem:
We have two servers one upstream and one reserved. Image that upstream server shutdowns. In this case socket on our side can be in CLOSE_WAIT state for a long period. If new request come we should send it to reserved server, but now we send it to shut downing upstream server