[Distutils] Entry points: specifying and caching

[Thomas Kluyver]

On Thu, Oct 19, 2017, at 04:10 PM, Donald Stufft wrote:
> I’m in favor, although one question I guess is whether it should be a a
> PEP or an ad hoc spec. Given (2) it should *probably* be a a PEP (since
> without (2), its just another file in the .dist-info directory and that
> doesn’t actually need standardized at all). I don’t think that this will
> be a very controversial PEP though, and should be pretty easy.

I have opened a PR to document what is already there, without adding any
new features. I think this is worth doing even if we don't change
anything, since it's a de-facto standard used for different tools to
interact.

https://github.com/pypa/python-packaging-user-guide/pull/390

We can still write a PEP for caching if necessary.

> I’m also in favor of this. Although I would suggest SQLite rather than a
> JSON file for the primary reason being that a JSON file isn’t
> multiprocess safe without being careful (and possibly introducing
> locking) whereas SQLite has already solved that problem.

SQLite was actually my first thought, but from experience in Jupyter &
IPython I'm wary of it - its built-in locking does not work well over
NFS, and it's easy to corrupt the database. I think careful use of
atomic writing can be more reliable (though that has given us some
problems too).

That may be easier if there's one cache per user, though - we can
perhaps try to store it somewhere that's not NFS.

Thomas