[Python-Dev] PEP 556: Threaded garbage collection

[Nathaniel Smith]

On Fri, Sep 8, 2017 at 12:13 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Fri, 08 Sep 2017 12:04:10 -0700
> Benjamin Peterson <benjamin at python.org> wrote:
>> I like it overall.
>>
>> - I was wondering what happens during interpreter shutdown. I see you
>> have that listed as a open issue. How about simply shutting down the
>> finalization thread and not guaranteeing that finalizers are actually
>> ever run à la Java?
>
> I don't know.  People generally have expectations towards stuff being
> finalized properly (especially when talking about files etc.).
> Once the first implementation is devised, we will know more about
> what's workable (perhaps we'll have to move _PyGC_Fini earlier in the
> shutdown sequence?  perhaps we'll want to switch back to serial mode
> when shutting down?).

PyPy just abandons everything when shutting down, instead of running
finalizers. See the last paragraph of :
http://doc.pypy.org/en/latest/cpython_differences.html#differences-related-to-garbage-collection-strategies

So that might be a useful source of experience.

On another note, I'm going to be that annoying person who suggests
massively extending the scope of your proposal. Feel free to throw
things at me or whatever.

Would it make sense to also move signal handlers to run in this
thread? Those are the other major source of nasty re-entrancy
problems.

-n

-- 
Nathaniel J. Smith -- https://vorpus.org