Background

When attempting to retrieve a listener socket's backlog queue length, we don't attempt to first check if the socket is TCP. The concept of a backlog queue length only exists in TCP and is not seen on Unix-domain sockets.

Problem caused

When starting up, the server will emit

"Error accepting new connection","attr":{"error":"Operation not supported"}

for each non-TCP listener. This will have no effect on the livelihood of these listeners, as the server swallows the error and recovers immediately.

Solution

Check if the socket is TCP after retrieving the acceptor record for a particular listener. If the socket is not TCP, do nothing. If it is, attempt to retrieve the backlog queue length.