[Python-Dev] Why is pickle.DEFAULT_PROTOCOL still 3?

[Antoine Pitrou]

On Mon, 2 Apr 2018 13:48:46 -0700
Lukasz Langa <lukasz at langa.pl> wrote:
> Pickle protocol version 4.0 was originally defined back in PEP 3154 and shipped as part of Python 3.4 back in 2011. Yet it's still not the default.

Because we want pickles produced with the default to be readable by
earlier Python 3 versions.
(the same reason protocol 0 stayed the default throughout the Python 2
lifetime)

Regards

Antoine.