Fix race condition when declaring parameters

[JafarAbdi]

Description

Fix: #474

Not an optimal solution at all, but at least it works :D

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extend the tutorials / documentation reference
• Document API changes relevant to the user in the MIGRATION.md notes
• Create tests, which fail without this PR reference
• Include a screenshot if changing a GUI
• While waiting for someone to review your request, please help review another open pull request to support the maintainers

[tylerjw]

Why would a node have already declared these parameters?

[JafarAbdi]

Why would a node have already declared these parameters?

Not 100% sure, but I think this mainly happens for RViz since each display will load its own robot model and they all share the same node causing multiple declarations

[codecov]

Codecov Report

Merging #525 (0924589) into main (656180d) will decrease coverage by 0.07%.
The diff coverage is n/a.

❗ Current head 0924589 differs from pull request most recent head da2f124. Consider uploading reports for the commit da2f124 to get more accurate results

@@            Coverage Diff             @@
##             main     #525      +/-   ##
==========================================
- Coverage   54.24%   54.18%   -0.06%     
==========================================
  Files         192      192              
  Lines       20224    20187      -37     
==========================================
- Hits        10969    10936      -33     
+ Misses       9255     9251       -4     

Impacted Files	Coverage Δ
...eit_core/robot_trajectory/src/robot_trajectory.cpp	15.75% <0.00%> (-7.38%)	⬇️
...dl_kinematics_plugin/src/kdl_kinematics_plugin.cpp	74.72% <0.00%> (-1.13%)	⬇️
...bot_state/include/moveit/robot_state/robot_state.h	88.89% <0.00%> (-1.05%)	⬇️
...nning_scene_monitor/src/planning_scene_monitor.cpp	45.49% <0.00%> (-0.32%)	⬇️
...anning_scene_monitor/src/current_state_monitor.cpp	74.18% <0.00%> (-0.22%)	⬇️
...it/planning_scene_monitor/planning_scene_monitor.h	33.34% <0.00%> (ø)
...on_distance_field/collision_distance_field_types.h	61.06% <0.00%> (ø)
moveit_ros/moveit_servo/src/servo_node.cpp
moveit_ros/moveit_servo/src/servo_server.cpp	78.95% <0.00%> (ø)

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[henningkayser]

So... RViz is initializing the plugins in separate threads with the same node instance? Well.. this is definitely another requirement for our WIP parameter API

[v4hn]

We actually have interfaces for sharing a RobotModel(Loader) in static memory.
Wouldn't it make sense to migrate the plugins to use moveit::planning_interface::getSharedRobotModel() instead of fixing the racing condition via catching exceptions?

[JafarAbdi]

I ended up fixing it by adding a shared robot model loaders, hopefully, this's a better solution than the previous one

[henningkayser]

Solution looks good to me. Please verify if we should or should not load IK solvers for the shared robot model