EXIT messages from sockets...?

[Adam Aquilon]

Hi all,

Does anyone know if Socket processes can send EXIT signals
to their owners, and if so, what kind of messages that may
be sent?

Also, under which circumstances can a listening port be 
closed by the Erlang VM or the OS?



Background:

I have a server listening to a TCP port (i.e. owns a listening
socket). The server spawns off processes handling each new
client that connects to this port in the standard, time-honored
fashion.

Sometimes, usually during high load it seems, the server that
owns the listening socket gets a message looking like this:

   {'EXIT',#Port<N,NNNN>,normal}

After this, the port is closed (note that it *can* be reopened
successfully).

I've seen that some pieces of kernel code seem to guard against
this kind of thing happning, for instance in inet_db.erl:

handle_info({'EXIT', Socket, _}, State) when port(Socket) ->
    ets:delete(inet_db, {socket,Socket}),
    {noreply, State};

But the documentation doesn't seem to mention that such things
can happen. Any light shed over this behaviour will be 
appreciated.

Regards,
Adam Aquilon