[Python-Dev] bpo-34837: Multiprocessing.Pool API Extension - Pass Data to Workers w/o Globals

[Chris Jerdonek]

On Thu, Oct 18, 2018 at 9:11 AM Michael Selik <michael.selik at gmail.com> wrote:
> On Thu, Oct 18, 2018 at 8:35 AM Sean Harrington <seanharr11 at gmail.com> wrote:
>> Further, let me pivot on my idea of __qualname__...we can use the `id` of `func` as the cache key to address your concern, and store this `id` on the `task` tuple (i.e. an integer in-lieu of the `func` previously stored there).
>
>
> Possible. Does the Pool keep a reference to the passed function in the main process? If not, couldn't the garbage collector free that memory location and a new function could replace it? Then it could have the same qualname and id in CPython. Edge case, for sure. Worse, it'd be hard to reproduce as it'd be dependent on the vagaries of memory allocation.

I'm not following this thread closely, but I just wanted to point out
that __qualname__ won't necessarily be an attribute of the object if
the API accepts any callable. (I happen to be following an issue on
the tracker where this came up.)

--Chris