Using rclpy.spin_once and await in a coroutine causes busy waiting #1405
Description
I noticed that when an executor is executing a coroutine which called await, all calls to rclpy.spin_once end immediately, causing busy waiting which results in 100% CPU consumption. Here's a script that demonstrates this issue:
import rclpy
import rclpy.logging
from rclpy.task import Future
from rclpy.executors import SingleThreadedExecutor
from rclpy.node import Node
async def coroutine():
print("Coroutine")
future = Future()
await future
rclpy.init()
rclpy.logging.set_logger_level("rcl", rclpy.logging.LoggingSeverity.DEBUG)
node = Node("test_node")
node.get_logger().set_level(rclpy.logging.LoggingSeverity.DEBUG)
node.create_timer(1.0, coroutine)
# This causes busy waiting
while rclpy.ok():
rclpy.spin_once(node)
# # This does not
# rclpy.spin(node)
# # This does not either
# executor = SingleThreadedExecutor()
# executor.add_node(node)
# while rclpy.ok():
# executor.spin_once()
node.destroy_node()
rclpy.shutdown()Tried it in Humble, Iron, Jazzy and Rolling, getting the same result every time.
I suspect the issue might be with the way the __async__ method in Future objects is implemented:
https://github.com/ros2/rclpy/blob/rolling/rclpy/rclpy/task.py#L73-L77
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