I'm have a wierd error in my code. It's extremely rare (happens once every few weeks maybe), but it's there and I'm not sure why.

We have 2 threads running, 1 thread gets networked messages and adds them to a Queue like this:

DataMessages.Enqueue(new DataMessage(client, msg));

Another thread takes messages off this queue and handles them, like this:

while (NetworkingClient.DataMessages.Count > 0)
{
    DataMessage message = NetworkingClient.DataMessages.Dequeue();

    switch (message.messageType)
    {
       ...
    }
}

However once every so often I get a NullReferenceException on the line switch (message.messageType) and I can see in the debugger that message is null.

It is not possible that a null value was put onto the queue (see the first bit of code), and these are the only 2 things that use the queue.

Is Queue not thread-safe, could it be that I'm dequeuing at the exact moment that the other thread is enqueuing and this causes the glitch?

c# .net multithreading queue
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