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

Eric Snow ericsnowcurrently at gmail.com
Tue Sep 12 16:48:54 EDT 2017

Yep.  See http://bugs.python.org/issue10915 and
http://bugs.python.org/issue15751.  The issue of C-extension support
for subinterpreters is, of course, a critical one here.  At the very
least, incompatible modules should be able to opt out of
subinterpreter support.  I've updated the PEP to discuss this.


On Sun, Sep 10, 2017 at 3:18 AM, Ronald Oussoren <ronaldoussoren at mac.com> wrote:
>> On 8 Sep 2017, at 05:11, Eric Snow <ericsnowcurrently at gmail.com> wrote:
>> On Thu, Sep 7, 2017 at 3:48 PM, Nathaniel Smith <njs at pobox.com> wrote:
>>> Numpy is the one I'm
>>> most familiar with: when we get subinterpreter bugs we close them
>>> wontfix, because supporting subinterpreters properly would require
>>> non-trivial auditing, add overhead for non-subinterpreter use cases,
>>> and benefit a tiny tiny fraction of our users.
>> The main problem of which I'm aware is C globals in libraries and
>> extension modules.  PEPs 489 and 3121 are meant to help but I know
>> that there is at least one major situation which is still a blocker
>> for multi-interpreter-safe module state.  Other than C globals, is
>> there some other issue?
> There’s also the PyGilState_* API that doesn't support multiple interpreters.
> The issue there is that callbacks from external libraries back into python
> need to use the correct subinterpreter.
> Ronald

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