A comment in nsd/driver.c states:
* Hint: NsQueueConn may fail to queue a certain
* socket to the designated connection queue.
* In such case, ALL ready sockets will be put on
* the waiting list until the next interation,
* regardless of which connection queue they are
* to be queued.
This may be a problem for quick error reponses (Server
Busy, Error etc.), whose connection now needs to be
kept open, consuming resources, when an empty queue
exists which could service the request.