Why is my UDPClient null once in a while

Question

Can someone explain to me why this code fails once in a while with a null exception for udpLink while sending?

            udpLink = new UdpClient(ipAddress, 514);
            using (udpLink)
            {
                  udpLink.Send(rawMsg, rawMsg.Length);
            }

This is the new code on how I fixed it.

            udpLink = new UdpClient(ipAddress, 514);
            using (udpLink)
            {
                  if (udpLink != null) udpLink.Send(rawMsg, rawMsg.Length);
            }

Any ideas?

Answer 1

I'm not sure if it really is the problem, but I guess it's the way how you use the using statement. I would do it like this:

using (UdpClient udpLink = new UdpClient(ipAddress, 514))
{
    udpLink.Send(rawMsg, rawMsg.Length);
}

Answer 2

Depending on whether or not this code segment is in a loop that executes thousands of times you might be maxing out on connections (speaking from experience). you can do a netstat -an and if it scrolls for more than a second chances are that could be your problem.

Answer 3

I don't see any reason why you should be getting a null pointer exception on udpLink. You are sure its udpLink that is null and not rawMsg? Also, you're sure you are throwing a NullPointerException and not a SocketException or other exception?