Executor cannot handle asyncio.sleep() in coroutine #279
Description
Bug report
Required Info:
- Operating System:
- Ubuntu 16.04 and Ubuntu 18.04
- Installation type:
- source
- Version or commit hash:
- DDS implementation:
- Fast-RTPS
- Client library (if applicable):
- rclpy
Steps to reproduce issue
With a ROS 2 workspace built and sourced:
- Create
foo_service.pywith the following content:
import asyncio
from example_interfaces.srv import AddTwoInts
import rclpy
async def add_two_ints_callback(request, response):
response.sum = request.a + request.b
await asyncio.sleep(1)
print('Service request handled')
return response
def main():
rclpy.init()
node = rclpy.create_node('foo_service')
srv = node.create_service(AddTwoInts, 'add_two_ints', add_two_ints_callback)
rclpy.spin(node)
rclpy.shutdown()
if __name__ == '__main__':
main()-
Run the service:
python3 foo_service.py -
Run a service client:
ros2 run examples_rclpy_minimal_client client
Expected behavior
Service call succeeds without error.
Actual behavior
Service server crashes from assertion error:
AssertionError: yield from wasn't used with future
Trace:
Traceback (most recent call last):
File "service.py", line 27, in <module>
main()
File "service.py", line 22, in main
rclpy.spin(node)
File "/home/jacob/ws/actions_ws/install/rclpy/lib/python3.5/site-packages/rclpy/__init__.py", line 119, in spin
executor.spin_once()
File "/home/jacob/ws/actions_ws/install/rclpy/lib/python3.5/site-packages/rclpy/executors.py", line 573, in spin_once
raise handler.exception()
File "/home/jacob/ws/actions_ws/install/rclpy/lib/python3.5/site-packages/rclpy/task.py", line 207, in __call__
self._handler.send(None)
File "/home/jacob/ws/actions_ws/install/rclpy/lib/python3.5/site-packages/rclpy/executors.py", line 324, in handler
await call_coroutine(entity, arg)
File "/home/jacob/ws/actions_ws/install/rclpy/lib/python3.5/site-packages/rclpy/executors.py", line 282, in _execute_service
response = await await_or_execute(srv.callback, request, srv.srv_type.Response())
File "/home/jacob/ws/actions_ws/install/rclpy/lib/python3.5/site-packages/rclpy/executors.py", line 89, in await_or_execute
return await callback(*args)
File "service.py", line 11, in add_two_ints_callback
await asyncio.sleep(1)
File "/usr/lib/python3.5/asyncio/tasks.py", line 516, in sleep
return (yield from future)
File "/usr/lib/python3.5/asyncio/futures.py", line 362, in __iter__
assert self.done(), "yield from wasn't used with future"
AssertionError: yield from wasn't used with future
Additional information
The error appears related to the call to asyncio.sleep(1) in the service server callback.
If we replace it with time.sleep(1), the code executes without error.