The function IncludeLaunchDescription in ROS Humble run launch file twice!

asked 2022-06-16 21:47:06 -0600

BlueBird gravatar image

updated 2022-06-17 03:34:05 -0600

ljaniec gravatar image

Required Info:

  • Operating System:
    • Ubuntu 22.04 LTS
    • Ros2 Humble
  • Installation type:
    • binaries
  • Client library (if applicable):
    • IncludeLaunchDescription of launch.actions

Steps to reproduce issue

test.launch.py -->

import os 

from ament_index_python.packages import get_package_share_directory 

from launch import LaunchDescription

from launch.actions import IncludeLaunchDescription 

from launch.launch_description_sources import PythonLaunchDescriptionSource

def generate_launch_description():

    ld = LaunchDescription()

    default_launch_file_path = os.path.join(get_package_share_directory('robot_bringup'), 'launch')

    start_test2_cmd = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(default_launch_file_path, 'test2.launch.py')
        )
    )
    ld.add_action(start_test2_cmd)

    return ld

test2.launch.py -->

import os

from launch import LaunchDescription

def generate_launch_description():

    ld = LaunchDescription()

    print("I only need to run once.")

    return ld

Expected behavior

  bluebird@bluebird-Jammy:~/Documents/InClassProjects/turtle_bot_ws$ ros2 launch robot_bringup test.launch.py 

  [INFO] [launch]: All log files can be found below /home/bluebird/.ros/log/2022-06-17-10-17-38-337096-bluebird-Jammy-22777

  [INFO] [launch]: Default logging verbosity is set to INFO

I only need to run once.

Actual behavior

bluebird@bluebird-Jammy:~/Documents/InClassProjects/turtle_bot_ws$ ros2 launch robot_bringup test.launch.py 

[INFO] [launch]: All log files can be found below /home/bluebird/.ros/log/2022-06-17-10-17-38-337096-bluebird-Jammy-22777

[INFO] [launch]: Default logging verbosity is set to INFO

I only need to run once.

I only need to run once.
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Comments

My process reminds me that the following codes seem run only once.

import os from launch import LaunchDescription import launch

test2.launch.py --> ``` def generate_launch_description():

ld = LaunchDescription()

print_cmd = launch.actions.ExecuteProcess(
    cmd=['echo', 'I only need to run once.'], output='screen', shell=True)

ld.add_action(print_cmd)

return ld

```

We have the following results. Results

That is true, but why does the print function run twice?

BlueBird gravatar image BlueBird  ( 2022-06-18 09:01:59 -0600 )edit
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