PicklingError: Can't pickle Task

[Johannes Maron]

Hi there,

I am working on Django tasks executor and noticed that the current implementation has a few oddities and bugs that we might want to address in future releases.

For now, let's focus on the biggest one, Tasks, and therefore TasksResults can't be pickled.
However, it is essential to use multiprocessing and to utilize the entire CPU to execute tasks.

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "$HOME/.local/share/uv/python/cpython-3.14.0-macos-aarch64-none/lib/python3.14/multiprocessing/reduction.py", line 51, in dumps
    cls(buf, protocol).dump(obj)
    ~~~~~~~~~~~~~~~~~~~~~~~^^^^^
_pickle.PicklingError: Can't pickle <function cpu_heavy_task at 0x10986eae0>: it's not the same object as tests.testapp.tasks.cpu_heavy_task

Of course, you can serialize and deserialize objects yourself, but that's a pretty high bar to clear.
Especially since it's a fairly easy fix for Django.

Cheers!
Joe

[Johannes Maron]

Note: IMHO this also cannot be solved with subclassing Task or TaskResult.

[Jacob Walls]

Hey Joe, this one is almost ready to merge, just would like a confirming review from someone. Fancy a look? ​PR

Duplicate of #36919