run_in_executor not stopping thread after task cancellation in asyncio (Python 3.11)

[dvir3211]

Bug report

A clear and concise description of the bug

The run_in_executor function in asyncio does not stop the thread after task cancellation.

Steps to Reproduce

import asyncio
import time

def runner():
    while True:
        print('Running.')
        time.sleep(1)

async def test():
    task = asyncio.get_event_loop().run_in_executor(None, runner)
    task.cancel()
    await task

asyncio.get_event_loop().run_until_complete(test()) 

Expected Behavior

The run_in_executor function should stop the thread and terminate the task when it is canceled.

Actual Behavior

The run_in_executor function does not stop the thread and the task continues to run even after it is canceled.

Your environment

• CPython versions tested on: python3.11
• Operating system and architecture: macOS M1

[dvir3211]

?

[sunmy2019]

https://docs.python.org/3/library/asyncio-task.html#task-cancellation

Tasks can easily and safely be cancelled. When a task is cancelled, asyncio.CancelledError will be raised in the task at the next opportunity.

Doc says at the next opportunity. This is usually an await point/get the result point of the future.

It means the exception is raised at

    await task # <----- here

But your task is running on another thread, it has no opportunity to find this asyncio.CancelledError.

[sunmy2019]

Let's just say, can you find any line in

def runner():
    while True:
        print('Running.')
        time.sleep(1)

that can raise an asyncio.CancelledError exception?

    await task # <----- here

Only this line is able to raise an asyncio.CancelledError

[gvanrossum]

Yeah, you cannot cancel a task that never calls await.

It's the same without asyncio:

import concurrent.futures
f = concurrent.futures.ThreadPoolExecutor(runner)
f.cancel()

doesn't interrupt that runner function either.