On Tue, 3 Apr 2018 at 01:19 Serhiy Storchaka <storch...@gmail.com> wrote:
> 03.04.18 01:57, Lukasz Langa пише: > >> On Apr 2, 2018, at 2:13 PM, Antoine Pitrou <solip...@pitrou.net> wrote: > >> On Mon, 2 Apr 2018 13:48:46 -0700 > >> Lukasz Langa <luk...@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) > > > > Alright, so that means we can easily do this for Python 3.8, right? I > mean, following Christian's logic, Python 3.3 is already dead, with its > final release done in February 2016 and support dropped in September 2017 > per PEP 398. > > > > I think we need to get past thinking about "Python 2" vs. "Python 3". > This frame of mind creates space for another mythical release of Python > that will break all the compatibilities, something we promised not to do. A > moving backward compatibility window that includes the last release still > under security fixes seems like a good new framework for this. > > > > What do you think? > > The only possible drawback of protocol 4 is that very short pickles can > be longer than with protocol 3 due to additional 9 bytes for the FRAME > header and less compact pickling of globals. > > This may be partially compensated by implementing additional > optimizations and/or passing short pickles through pickletools.optimize(). > I think if you're that worried about specifics to that detail then you should be specifying the protocol level manually anyway. I view this like something in the peepholer: a freebie perf bump for those that aren't too worried about such things. :)
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