[Core] Add more user-friendly error message upon async def remote task #13687
Description
Describe your feature request
The script
import ray
ray.init()
@ray.remote
async def f():
pass
ray.get(f.remote())outputs the following error:
(pid=86346) /Users/archit/ray/python/ray/worker.py:390: RuntimeWarning: coroutine 'f' was never awaited
(pid=86346) self.core_worker.run_task_loop()
2021-01-25 10:41:35,193 ERROR worker.py:1053 -- Possible unhandled error from worker: ray::f() (pid=86346, ip=192.168.1.4)
File "python/ray/_raylet.pyx", line 509, in ray._raylet.execute_task
File "python/ray/_raylet.pyx", line 510, in ray._raylet.execute_task
File "python/ray/_raylet.pyx", line 1466, in ray._raylet.CoreWorker.store_task_outputs
File "/Users/archit/ray/python/ray/serialization.py", line 319, in serialize
return self._serialize_to_msgpack(value)
File "/Users/archit/ray/python/ray/serialization.py", line 299, in _serialize_to_msgpack
self._serialize_to_pickle5(metadata, python_objects)
File "/Users/archit/ray/python/ray/serialization.py", line 259, in _serialize_to_pickle5
raise e
File "/Users/archit/ray/python/ray/serialization.py", line 256, in _serialize_to_pickle5
value, protocol=5, buffer_callback=writer.buffer_callback)
File "/Users/archit/ray/python/ray/cloudpickle/cloudpickle_fast.py", line 73, in dumps
cp.dump(obj)
File "/Users/archit/ray/python/ray/cloudpickle/cloudpickle_fast.py", line 574, in dump
return Pickler.dump(self, obj)
TypeError: can't pickle coroutine objectsThe error message could say not to use async def for remote tasks, and maybe it could also suggest wrapping the task in an async actor.