[Distutils] GSoC 2017 - Working on pip

[David Cournapeau]

On Fri, Feb 10, 2017 at 2:33 PM, Justin Cappos <jcappos at nyu.edu> wrote:

> Yes, don't use a SAT solver.  It requires all metadata from all packages
> (~30MB uncompressed) and gives hard to predict results in some cases.
>

I doubt there exists an algorithm where this is not the case.

  Also the lack of fixed dependencies is a substantial problem for a SAT
> solver.  Overall, we think it makes more sense to use a simple backtracking
> dependency resolution algorithm.
>

As soon as you want to deal with version ranges and ensure consistency of
the installed packages, backtracking stops being simple rather quickly.

I agree lack of fixed dependencies is an issue, but I doubt it is specific
to a SAT solver. SAT solvers have been used successfully in many cases now:
composer (php), dnf (Red Hat/Fedora), conda or our own packages manager at
Enthought in python, 0install.

I would certainly be interested in seeing a proper comparison with other
algorithms.

David


> Sebastien Awwad (CCed) has been looking at a bunch of data around the
> speed and other tradeoffs of the different algos.  Sebastien:  Sometime
> next week, can you write it up in a way that is suitable for sharing?
>
> Justin
>
> On Fri, Feb 10, 2017 at 1:59 PM, Wes Turner <wes.turner at gmail.com> wrote:
>
>> From the discussion on https://github.com/pypa/pip/is
>> sues/988#issuecomment-279033079:
>>
>>
>>    - https://github.com/ContinuumIO/pycosat (picosat)
>>       - https://github.com/ContinuumIO/pycosat/blob/master/pycosat.c (C)
>>       - https://github.com/ContinuumIO/pycosat/blob/master/picosat.c
>>       - https://github.com/ContinuumIO/pycosat/tree/master/examples
>>    - https://github.com/enthought/sat-solver (MiniSat)
>>       - https://github.com/enthought/sat-solver/tree/master/simplesa
>>       t/tests
>>       - https://github.com/enthought/sat-solver/blob/master/requirem
>>       ents.txt (PyYAML, enum34)
>>
>>
>> Is there a better way than SAT?
>>
>> On Fri, Feb 10, 2017 at 12:20 PM, Pradyun Gedam <pradyunsg at gmail.com>
>> wrote:
>>
>>> Yay! Thank you so much for a prompt and positive response! I'm pretty
>>> excited and looking forward to this.
>>>
>>> On Thu, Feb 9, 2017, 20:23 Donald Stufft <donald at stufft.io> wrote:
>>>
>>> I’ve never done it before, but I’m happy to provide mentoring on this.
>>>
>>> On Feb 8, 2017, at 9:15 PM, Pradyun Gedam <pradyunsg at gmail.com> wrote:
>>>
>>> Hello Everyone!
>>>
>>> Ralf Gommers suggested that I put this proposal here on this list, for
>>> feedback and for seeing if anyone would be willing to mentor me. So, here
>>> it is.
>>>
>>> -----
>>>
>>> My name is Pradyun Gedam. I'm currently a first year student VIT
>>> University in India.
>>>
>>> I would like to apply for GSoC 2017 under PSF.
>>>
>>> I currently have a project in mind - the "pip needs a dependency
>>> resolver" issue [1]. I would like to take on this specific project but am
>>> willing to do some other project as well.
>>>
>>> For some background, around mid 2016, I started contributing to pip. The
>>> first issue I tackled was #59 [2] - a request for upgrade command and an
>>> upgrade-all command that has been open for over 5.5 years. Over the months
>>> following that, I've have had the opportunity to work with and understand
>>> multiple parts of pip's codebase while working on this issue and a few
>>> others. This search on GitHub issues [3] also provides a good summary of
>>> what work I've done on pip.
>>>
>>> [2]: https://github.com/pypa/pip/issues/988
>>> [2]: https://github.com/pypa/pip/issues/59
>>> [3]: https://github.com/pypa/pip/issues?q=author%3Apradyunsg
>>>
>>> Eagerly-waiting-for-a-response-ly,
>>> Pradyun Gedam
>>>
>>> _______________________________________________
>>> Distutils-SIG maillist  -  Distutils-SIG at python.org
>>> https://mail.python.org/mailman/listinfo/distutils-sig
>>>
>>>
>>>
>>> —
>>>
>>> Donald Stufft
>>>
>>>
>>> _______________________________________________
>>> Distutils-SIG maillist  -  Distutils-SIG at python.org
>>> https://mail.python.org/mailman/listinfo/distutils-sig
>>>
>>>
>>
>> _______________________________________________
>> Distutils-SIG maillist  -  Distutils-SIG at python.org
>> https://mail.python.org/mailman/listinfo/distutils-sig
>>
>>
>
> _______________________________________________
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>
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