Hey all,
Discovered what I believe is a bug in the Ruby Mongo Driver
version 1.0.1 in Mongo::Connection. The function connect_to_master
creates a socket that it leaves dangling until the Ruby process that
is using Mongo exits. I write up a fix to add that specific socket to
the @sockets variable. I also think there is a separate bug where
multiple threads invoking connect_to_master at exactly the same time
causing multiple sockets to get created in parallel, potentially
exceeding the pool limit.

Attached is my attempt at a fix. Would love to know if others see
this dangling socket issue where ... you would see it as 1 or 2
permanent connections to mongo db for the life of your process ...
depending on whether you call db.logoff/m.close in your client code.

Greg

1. Create a new socket and attempt to connect to master.
2. If successful, sets host and port to master and returns the
   socket.
   #
3. @raise [ConnectionFailure] if unable to connect to any host or
   port.
   def connect_to_master
   close
   @host = @port = nil
   for node_pair in @nodes
   host, port = *node_pair
   begin

socket = nil
begin
socket = TCPSocket.new(host, port)
socket.setsockopt(Socket::IPPROTO_TCP,
Socket::TCP_NODELAY, 1)
rescue => ex
raise ConnectionFailure, "Failed to connect socket: #

"
end

1. If we're connected to master, set the @host and @port
   result = self['admin'].command({:ismaster => 1}, false,
   false, socket)
   if result['ok'] == 1 && ((is_master = result['ismaster'] ==
   1) || @slave_ok)
   @connection_mutex.synchronize do
   @host, @port = host, port
   @sockets << socket
   apply_saved_authentication
   end
   end

1. Note: slave_ok can be true only when connecting to a
   single node.
   if @nodes.length == 1 && !is_master && !@slave_ok
   raise ConfigurationError, "Trying to connect directly to
   slave; " +
   "if this is what you want, specify :slave_ok => true."
   end

break if is_master || @slave_ok
rescue SocketError, SystemCallError, IOError => ex
socket.close if socket
close
false
end
end
raise ConnectionFailure, "failed to connect to any given
host:port" unless socket
end