Gazebo /clock messages not recieved in ROS2 correctly when sent through ros1_bridge

[michalbahnik]

Hi, I experience some strange behavior connected to using Gazebo and ros1_bridge together. If I try to send /clock through the bridge to ROS2, big part of the messages are not recieved. I am not sure, if error is in the bridge or in gazebo plugin, but ROS1 topic is published (and can be recieved) correctly, unlike messsages transferred via bridge, so I suspect, something bad happens in bridge.

Bug report

Required Info:

• Operating System:
  • Ubuntu 20.04
• Installation type:
  • binaries
• Version or commit hash:
  • 0.9.3-1focal.20200722.060820
• DDS implementation:
  • N/A
• Client library (if applicable):
  • rclpy
• ROS versions
  • Noetic
  • Foxy
• Gazebo version
  • Gazebo 11

Steps to reproduce issue

1. Run test Gazebo world with ROS

rosrun gazebo_ros gazebo

2. Run ros1_bridge

ros2 run ros1_bridge dynamic_bridge /clock

3. Run minimal subscriber for /clock topic.

#!/usr/bin/env python
import rclpy
from rclpy.node import Node

from rosgraph_msgs.msg import Clock

class MinimalSubscriber(Node):

    def __init__(self):
        super().__init__('minimal_subscriber')
        self.subscription = self.create_subscription(
            Clock,
            '/clock',
            self.listener_callback,
            10)
        self.subscription  # prevent unused variable warning

    def listener_callback(self, msg: Clock):
        self.get_logger().info(f'I heard: "{msg}"')


def main(args=None):
    rclpy.init(args=args)

    minimal_subscriber = MinimalSubscriber()

    rclpy.spin(minimal_subscriber)

    minimal_subscriber.destroy_node()
    rclpy.shutdown()


if __name__ == '__main__':
    main()

4. Check frequency with

rostopic hz /clock

and

ros2 topic hz /clock

Expected behavior

Recieving frequency (ROS2) expected to be similar to publishing (ROS1) frequency ~ 1000 Hz.

Actual behavior

Messages recieved (ROS2) with much lower frequency (avg < 200).

Additional information

Clock messages are recieved correctly for some time (< 1 s) and then lag of few houndereds of miliseconds happens.

Note that if I run simple publisher (according to oficial tutorials), frequency matches. If I try this while Gazebo simulation is running (and publishing), frequency decreases again.

Thanks for any advises and/or fixes!

[dirk-thomas]

I tried to reproduce your problem with the following shells:

• ROS 1: roscore
• ROS 1: rosrun gazebo_ros gazebo
• ROS 1 and 2: ros2 run ros1_bridge dynamic_bridge (note: this executable does not accept a topic name as an argument, your /clock argument was simply ignored)
• ROS 2: ros2 topic echo /clock rosgraph_msgs/msg/Clock
• ROS 2: ros2 topic hz /clock

And I get an average rate of > 980 Hz.

Please try the above steps to check if the problem is related to your custom subscriber or something else.

[michalbahnik]

Hello @dirk-thomas , thank you for your answer! I replicated steps you posted above and I reached average rate of about 970 Hz. Then I also tried to use the listener script from my original answer and the performance was very similar. I believe there was something wrong with my ROS Noetic installation (including all gazebo packages), because I also experienced some other issues and in the end (after dealing with this issue) I reinstalled it. After reinstallation, ros1_bridge and gazebo works as expected.