Inconsistent output of “ros2 param list”
I'm currently running ROS2 Foxy in a Docker container on WSL2. I'm going through the ROS2 tutorials so I have nodes /turtlesim and /teleop_turtle running. For some reason, the output of ros2 param list is inconsistent - one or both of the nodes are occasionally excluded from the output. Rebooting the Docker container doesn't help. ros2 doctor says a fair amount of UserWarnings but ultimately says All 4 checks passed. Running ros2 daemon status before testing ros2 param list (as recommended here) does not resolve the issue. What is causing this param list issue, and how can I resolve it?
Environment
- OS: Windows 10 Home, version 10.0.19041 Build 19041
- Processor: Intel(R) Core(TM) i5-5200U CPU @ 2.20GHz, 2201 Mhz, 2 Core(s), 4 Logical Processor(s)
- Docker version: 19.03.13, build 4484c46d9d (full version info at bottom of post)
- Ubuntu version (WSL2): Ubuntu 20.04.1 LTS
- ROS2: from docker container, see below
Steps to reproduce issue
Open three terminals.
In terminal 1:
docker pull osrf/ros:foxy-desktop
xhost +local:root > /dev/null 2>&1
docker run -it -e DISPLAY -v /tmp/.X11-unix:/tmp/.X11-unix:rw osrf/ros:foxy-desktop
# I'm now inside container
ros2 run turtlesim turtlesim_node # start turtlesim_node
In terminal 2:
docker exec -it <container> bash -c "source /opt/ros/foxy/setup.bash && bash"
# I'm now inside container
ros2 run turtlesim turtle_teleop_key # start turtle_teleop_key
In terminal 3:
docker exec -it <container> bash -c "source /opt/ros/foxy/setup.bash && bash"
# I'm now inside container
while true; do ros2 param list; echo "*** separator ***"; done
Sample output from terminal 3, showing that sometimes one or both of the nodes are excluded from ros2 param list:
/teleop_turtle:
scale_angular
scale_linear
use_sim_time
/turtlesim:
background_b
background_g
background_r
use_sim_time
*** separator ***
/teleop_turtle:
scale_angular
scale_linear
use_sim_time
/turtlesim:
background_b
background_g
background_r
use_sim_time
*** separator ***
*** separator ***
/teleop_turtle:
scale_angular
scale_linear
use_sim_time
/turtlesim:
background_b
background_g
background_r
use_sim_time
*** separator ***
*** separator ***
/teleop_turtle:
scale_angular
scale_linear
use_sim_time
*** separator ***
/teleop_turtle:
scale_angular
scale_linear
use_sim_time
/turtlesim:
background_b
background_g
background_r
use_sim_time
*** separator ***
/turtlesim:
background_b
background_g
background_r
use_sim_time
*** separator ***
/teleop_turtle:
scale_angular
scale_linear
use_sim_time
/turtlesim:
background_b
background_g
background_r
use_sim_time
*** separator ***
/teleop_turtle:
scale_angular
scale_linear
use_sim_time
/turtlesim:
background_b
background_g
background_r
use_sim_time
*** separator ***
The output of while true; do ros2 node list; ros2 topic list; ros2 service list; echo "*** separator ***"; done is consistent, however (i.e. every iteration shows the below without any info being erroneously excluded):
/teleop_turtle
/turtlesim
/parameter_events
/rosout
/turtle1/cmd_vel
/turtle1/color_sensor
/turtle1/pose
/clear
/kill
/reset
/spawn
/teleop_turtle/describe_parameters
/teleop_turtle/get_parameter_types
/teleop_turtle/get_parameters
/teleop_turtle/list_parameters
/teleop_turtle/set_parameters
/teleop_turtle/set_parameters_atomically
/turtle1/set_pen
/turtle1/teleport_absolute
/turtle1/teleport_relative
/turtlesim/describe_parameters
/turtlesim/get_parameter_types
/turtlesim/get_parameters
/turtlesim/list_parameters
/turtlesim/set_parameters
/turtlesim/set_parameters_atomically
*** separator ***
Additional information
Docker version:
Client: Docker Engine - Community
Version: 19.03.13
API version: 1.40
Go version: go1.13.15
Git commit: 4484c46d9d
Built: Wed Sep 16 17:02:52 2020
OS/Arch: linux/amd64
Experimental: false
Server: Docker Engine - Community
Engine:
Version: 19.03.13
API version: 1.40 (minimum version 1.12)
Go version: go1.13.15
Git commit ...
Could you specifically point out what you see as inconsistent? Few folks are going to scan through 100 lines of terminal output to eye-spy the issues with ros2 param. Also may want to ensure that bidirectional ROS connectivity is working if your using multiple containers and various virtual network interfaces.
@ruffsl thank you for your comment. The issue is fairly straightforward;
ros2 param listsometimes excludes one or both of the 2 nodes running, and the terminal output demonstrates this. I've edited the post to make this more explicit. I am also using a single container and on one machine only, so I don't think your last point applies (correct me if I'm wrong).Ah, that is odd. If you can reproduce this issue on a separate machine, you may want to report is as an issue under this repo: https://github.com/ros2/ros2cli . My guess is that the daemon for the ros2cli is not being started, so each time an ros2cli command is run, it has to rediscover other ros2 nodes, a process that is made more consistent with use of a persistent running daemon to cache discovery info over time. See here for more info: https://answers.ros.org/question/3273...
@ruffsl Thank you for the helpful link. It seems I still have the same issue, even after following the recommendation to call
ros2 daemon statusbefore testingros2 param list. I do not have a separate machine with which to try reproducing at the moment, unfortunately.While Windows 10 is supported, and Ubuntu is supported, Docker-containers-on-Ubuntu-in-WSL2-on-Windows-10 is not part of the standard list of systems -- nor is it included in CI or testing rounds.
@DrakeP: is this reproducable on a regular Ubuntu machine? Or perhaps in a VM (I know WSL2 is technically a VM, but there's still some funky stuff going on inside it)? Both VMWare and VBox (fi) have free versions.