interpreters.InterpreterError: RuntimeError: _interpqueues module not imported yet

[Jamie-Chang]

Python version: 3.13 with gil enabled

I tried to follow examples in PEP-734 but couldn't pass the queue using Interpreter.prepare_main

To reproduce

from interpreters_backport import interpreters

interp = interpreters.create()
queue = interpreters.create_queue()
interp.prepare_main(queue=queue)

this gives us

interpreters.InterpreterError: RuntimeError: _interpqueues module not imported yet

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/jamie.chang/personal-projects/advent2024-python/queue_bug.py", line 5, in <module>
    interp.prepare_main(queue=queue)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/Users/jamie.chang/personal-projects/advent2024-python/.venv/lib/python3.13/site-packages/interpreters_backport/interpreters/__init__.py", line 211, in prepare_main
    _interpreters.set___main___attrs(self._id, ns, restrict=True)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
interpreters.InterpreterError: failed to apply namespace to __main__

I was able to workaround the issue by using the Queue.id inside the interpreter

from textwrap import dedent
from interpreters_backport import interpreters

interp = interpreters.create()
queue = interpreters.create_queue()
interp.exec(
    dedent(f"""
        from interpreters_backport import interpreters
        tasks = interpreters.Queue({queue.id})
    """)
)

Let me know if this is supposed to go to the upstream, I'm not sure if the issue is in the backport or cpython

[jhenstridge]

I ran into this too, using Python 3.13.0. Here is another workaround that worked for me:

interp.exec("import interpreters_backport.interpreters.queues")
interp.prepare_main(queue=queue)

I guess the problem here is that _interpqueues needs to have been imported by the new interpreter before the queue can be added to its namespace.