Cannot run asyncio.sleep in a greenlet

[sillydan1]

I want to run an asyncio-based function inside a greenlet but I am running into an issue where the eventloop is started whilst another is already running. Here's a minimal example:

import gevent.monkey
gevent.monkey.patch_all()
import asyncio
import asyncio_gevent

asyncio.set_event_loop_policy(asyncio_gevent.EventLoopPolicy())

import gevent

@asyncio_gevent.async_to_sync
async def async_main():
    await asyncio.sleep(1)


def main():
    gevent.joinall([
        gevent.spawn(async_main),
        gevent.spawn(async_main),
    ])

if __name__ == "__main__":
    main()

This will fail with the following output:

Traceback (most recent call last):
  File "src/gevent/greenlet.py", line 908, in gevent._gevent_cgreenlet.Greenlet.run
  File "/usr/local/lib/python3.11/asyncio/base_events.py", line 596, in run_forever
    self._check_running()
  File "/usr/local/lib/python3.11/asyncio/base_events.py", line 590, in _check_running
    raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
2024-01-26T10:07:42Z <Greenlet at 0x7fdd85be36a0: <bound method BaseEventLoop.run_forever of <EventLoop running=False closed=False debug=False>>> failed with RuntimeError

Traceback (most recent call last):
  File "src/gevent/greenlet.py", line 908, in gevent._gevent_cgreenlet.Greenlet.run
  File "/usr/local/lib/python3.11/asyncio/base_events.py", line 651, in run_until_complete
    raise RuntimeError('Event loop stopped before Future completed.')
RuntimeError: Event loop stopped before Future completed.
2024-01-26T10:07:42Z <Greenlet at 0x7fdd85be3560: <bound method BaseEventLoop.run_until_complete of <EventLoop running=False closed=False debug=False>>(<Task pending name='Task-2' coro=<async_main() run)> failed with RuntimeError

Traceback (most recent call last):
  File "src/gevent/greenlet.py", line 908, in gevent._gevent_cgreenlet.Greenlet.run
  File "/usr/local/lib/python3.11/site-packages/asyncio_gevent/future_to_greenlet.py", line 118, in _run
    return ensured_future.result()
           ^^^^^^^^^^^^^^^^^^^^^^^
asyncio.exceptions.InvalidStateError: Result is not set.
2024-01-26T10:07:42Z <Greenlet at 0x7fdd85be2de0: _run(future=<coroutine object async_main at 0x7fdd85d82980>, loop=None, autostart_future=True, on_cancelled=<function future_to_greenlet.<locals>.on_cancelled)> failed with InvalidStateError

Traceback (most recent call last):
  File "src/gevent/greenlet.py", line 908, in gevent._gevent_cgreenlet.Greenlet.run
  File "/usr/local/lib/python3.11/site-packages/asyncio_gevent/async_to_sync.py", line 37, in fn
    return greenlet.get()
           ^^^^^^^^^^^^^^
  File "src/gevent/greenlet.py", line 805, in gevent._gevent_cgreenlet.Greenlet.get
  File "src/gevent/greenlet.py", line 373, in gevent._gevent_cgreenlet.Greenlet._raise_exception
  File "/usr/local/lib/python3.11/site-packages/gevent/_compat.py", line 66, in reraise
    raise value.with_traceback(tb)
  File "src/gevent/greenlet.py", line 908, in gevent._gevent_cgreenlet.Greenlet.run
  File "/usr/local/lib/python3.11/site-packages/asyncio_gevent/future_to_greenlet.py", line 118, in _run
    return ensured_future.result()
    ^^^^^^^^^^^^^^^^^
asyncio.exceptions.InvalidStateError: Result is not set.
2024-01-26T10:07:42Z <Greenlet at 0x7fdd85be2ac0: fn> failed with InvalidStateError

sys:1: RuntimeWarning: coroutine 'async_main' was never awaited
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
Task was destroyed but it is pending!
task: <Task pending name='Task-2' coro=<async_main() running at /code/src/comsdk/cli/main.py:10>>

I suspect that I am using either asyncio, gevent or asyncio-gevent wrongly here.