facebook/tornado — pull request #923 by ribeiroit (2013-10-31 13:42:05+00:00)
Title: Suppressing LookupError: unknown encoding: latin1 on Mac 

There was a strange behavior on mac during many opened connections. So I just made a little change to suppress the error messages:

LookupError: unknown encoding: latin1
ERROR:tornado.application:Exception in callback

You won't get this error anymore whenever you run any stress-test.