[Python-ideas] PEP 554: Stdlib Module to Support Multiple Interpreters in Python Code

Nick Coghlan ncoghlan at gmail.com
Thu Sep 14 18:39:19 EDT 2017

On 14 September 2017 at 08:25, Nick Coghlan <ncoghlan at gmail.com> wrote:
> On 13 September 2017 at 20:45, Koos Zevenhoven <k7hoven at gmail.com> wrote:
>> It's still just *an* interpreter that happens to run __main__. And who says
>> it even needs to be the only one?
> Koos, I've asked multiple times now for you to describe the practical
> user benefits you believe will come from dispensing with the existing
> notion of a main interpreter (which is *not* something PEP 554 has
> created - the main interpreter already exists at the implementation
> level, PEP 554 just makes that fact visible at the Python level).

Eric addressed this in the latest update, and took the view that since
it's a question the can be deferred, it's one that should be deferred,
in line with the overall "minimal enabling infrastructure" philosophy
of the PEP.

On thinking about it further, I believe this may also intersect with
some open questions I have around the visibility of *thread* objects
across interpreters - the real runtime constraint at the
implementation level is the fact that we need a main *thread* in order
to sensibly manage the way signal handling works across different
platforms, and that's where we may get into trouble if we allow
arbitrary subinterpreters to run in the main thread, and accept and
process signals directly.


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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