Hello, I would like to call to your attention the following behavior of TextIOWrapper: import io def test(buf): textio = io.TextIOWrapper(buf) buf = io.BytesIO() test(buf) print(buf.closed) # This prints True currently The problem here is TextIOWrapper closes its buffer when deleted. BufferedRWPair behalves similarly. The solution is simply to override the __del__ method of TextIOWrapper inherited from IOBase. -- Alexandre