[Python-Dev] PEP 574 (pickle 5) implementation and backport available

[Ivan Pozdeev]

On 25.05.2018 20:36, Raymond Hettinger wrote:
>
>> On May 24, 2018, at 10:57 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
>>
>> While PEP 574 (pickle protocol 5 with out-of-band data) is still in
>> draft status, I've made available an implementation in branch "pickle5"
>> in my GitHub fork of CPython:
>> https://github.com/pitrou/cpython/tree/pickle5
>>
>> Also I've published an experimental backport on PyPI, for Python 3.6
>> and 3.7.  This should help people play with the new API and features
>> without having to compile Python:
>> https://pypi.org/project/pickle5/
>>
>> Any feedback is welcome.
> Thanks for doing this.
>
> Hope it isn't too late, but I would like to suggest that protocol 5 support fast compression by default.  We normally pickle objects so that they can be transported (saved to a file or sent over a socket). Transport costs (reading and writing a file or socket) are generally proportional to size, so compression is likely to be a net win (much as it was for header compression in HTTP/2).
>
> The PEP lists compression as a possible a refinement only for large objects, but I expect is will be a win for most pickles to compress them in their entirety.

I would advise against that. Pickle format is unreadable as it is, 
compression will make it literally impossible to diagnose problems.
Python supports transparent compression, e.g. with the 'zlib' codec.

>
> Raymond
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-- 
Regards,
Ivan