What I am expecting: I'm expecting myself to look at the messages players had been chatting about. Nothing more than chit-chats and some messages notifying me who disconnected and who joined.

What I see at the moment: I would usually get tons and tons of SocketExceptions and a few "disconnect.genericReason" messages along with player messages and chit-chat. Actually, the SocketExceptions took up more space in the console than the individual player messages seen.

How to reliably reproduce:

1. Run a Minecraft server.
2. Run Minecraft.
3. Use Minecraft to login to the server with "localhost" as IP (Or 127.0.0.1)
4. Do whatever you can to close Minecraft, such as pressing the red X button in Windows (Red button for Mac). *No need to pause and "Disconnect" from the server in the game, just simply shut the game down.*
5. Receive one instance of SocketException stack trace.
6. That same instance will not be logged to the "server.log"

A picture has been attached.

Consider what tons of players joining and quitting the game will do, as some of the players will just "X" out the game, outputting many SocketException instances.