librviz : Creating a MotionPlanning display in Noetic without crashing

[julien-audet]

Hello,

I've been using librviz successfully for the past two years in my own Qt application for the visualization of a robot doing finishing tasks in ROS Kinetic with Ubuntu 16.04. Here's a code snippet of how I initialized librviz classes and added rviz::Display objects :

    // Construct and lay out render panel.
    rviz_render_panel_ = new rviz::RenderPanel();

    // Next we initialize the main RViz classes.
    rviz_manager_ = new rviz::VisualizationManager(rviz_render_panel_);
    rviz_render_panel_->initialize(rviz_manager_->getSceneManager(), rviz_manager_);
    rviz_manager_->initialize();
    rviz_manager_->startUpdate();
    
    // Create a display for MotionPlanning
    moveit_display_ = rviz_manager_->createDisplay("moveit_rviz_plugin/MotionPlanning", "MotionPlanning", true);

This used to work very well, but I've recently migrated from Kinetic to Noetic, and now, the last line (createDisplay) crashes without any warning or error for "moveit_rviz_plugin/MotionPlanning". It still works with any other rviz::Display objects, but crashes everytime when using "MotionPlanning". If I use rViz directly, I can easily create a MotionPlanning display and do A to B trajectories. Interestingly enough, it doesn't crash if I disable the display (isEnabled -> false) :

    moveit_display_ = rviz_manager_->createDisplay("moveit_rviz_plugin/MotionPlanning", "MotionPlanning", false);

But it crashes as soon as I enable it : moveit_display__->setEnabled(true)

So, my question is :

Is the MotionPlanning display object deprecated in the Noetic version of librviz (I wouldn't think so since it works in rViz)?

You can easily replicate the error using the librviz tutorial :
https://github.com/ros-visualization/visualization_tutorials/tree/noetic-devel/librviz_tutorial
And adding the following line after manager_->startupdate() :
rviz_manager_->createDisplay("moveit_rviz_plugin/MotionPlanning", "MotionPlanning", true);
It results as a "Segmentation fault (core dumped)" in this case.

Using gdb :

Thread 1 "myviz" received signal SIGSEGV, Segmentation fault.
#0  0x00007ffff7a96932 in QWidget::show() ()
    at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#1  0x00007fff802005cf in moveit_rviz_plugin::MotionPlanningFrame::enable() ()
    at /opt/ros/noetic/lib/libmoveit_motion_planning_rviz_plugin_core.so.1.1.5
#2  0x00007ffff7783315 in rviz::Display::onEnableChanged() ()
    at /opt/ros/noetic/lib/librviz.so
#3  0x00007ffff776eab8 in  () at /opt/ros/noetic/lib/librviz.so
#4  0x00007ffff6c47300 in QMetaObject::activate(QObject*, int, int, void**) ()
    at /lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007ffff78054ab in rviz::Property::setValue(QVariant const&) ()
    at /opt/ros/noetic/lib/librviz.so
#6  0x00007ffff778311b in rviz::Display::setEnabled(bool) ()
    at /opt/ros/noetic/lib/librviz.so
#7  0x00007ffff7862b28 in rviz::VisualizationManager::createDisplay(QString const&, QString const&, bool) () at /opt/ros/noetic/lib/librviz.so
#8  0x000055555556921c in MyViz::MyViz(QWidget*)
...

Using valgrind :

==10405== Invalid read of size 8
==10405==    at 0x4A32932: QWidget::show() (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.12.8)
==10405==    by 0x2F5525CE: moveit_rviz_plugin::MotionPlanningFrame::enable() (in /opt/ros/noetic/lib/libmoveit_motion_planning_rviz_plugin_core.so.1.1.5)
==10405==    by 0x502E314: rviz::Display::onEnableChanged() (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x5019AB7: ??? (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x5BE72FF: QMetaObject::activate(QObject*, int, int, void**) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.12.8)
==10405==    by 0x50B04AA: rviz::Property::setValue(QVariant const&) (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x502E11A: rviz::Display::setEnabled(bool) (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x510DB27: rviz::VisualizationManager::createDisplay(QString const&, QString const&, bool) (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x11D21B: MyViz::MyViz(QWidget*) (myviz.cpp:62)
==10405==    by 0x123073: main (main.cpp:14)
==10405==  Address 0x28 is not stack'd, malloc'd or (recently) free'd
==10405== 
==10405== 
==10405== Process terminating with default action of signal 11 (SIGSEGV)
==10405==  Access not within mapped region at address 0x28
==10405==    at 0x4A32932: QWidget::show() (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.12.8)
==10405==    by 0x2F5525CE: moveit_rviz_plugin::MotionPlanningFrame::enable() (in /opt/ros/noetic/lib/libmoveit_motion_planning_rviz_plugin_core.so.1.1.5)
==10405==    by 0x502E314: rviz::Display::onEnableChanged() (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x5019AB7: ??? (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x5BE72FF: QMetaObject::activate(QObject*, int, int, void**) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.12.8)
==10405==    by 0x50B04AA: rviz::Property::setValue(QVariant const&) (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x502E11A: rviz::Display::setEnabled(bool) (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x510DB27: rviz::VisualizationManager::createDisplay(QString const&, QString const&, bool) (in /opt/ros/noetic/lib/librviz.so)
==10405==    by 0x11D21B: MyViz::MyViz(QWidget*) (myviz.cpp:62)
==10405==    by 0x123073: main (main.cpp:14)

I've investigated a bit and it seems like the parent QWidget of the MotionPlanningFrame is not initialized correctly (nullptr). Should I ask the question at the moveit repository?

Here's the link to the cpp files :
MotionPlanningFrame
MotionPlanningDisplay

At line 229 of MotionPlanningDisplay, we have the initialization of MotionPlanningFrame :

rviz::WindowManagerInterface* window_context = context_->getWindowManager();
frame_ = new MotionPlanningFrame(this, context_, window_context ? window_context->getParentWindow() : nullptr);

I guess the last argument of the second line is where the parent QWidget is initialized to a nullptr. context_ (rviz::DisplayContext) comes from the base class of MotionPlanningDisplay, that is rviz::Display, so I wouldn't think it is the problem.

Now, I've built Moveit from source and it seems like window_context is a nullptr. Is getWindowManager() deprecated?

Your environment

• OS Version: Ubuntu 20.04
• ROS Distro: Noetic
• RViz, Qt, OGRE, OpenGl version as printed by rviz:
  [ INFO] [1628191103.549857876]: rviz version 1.14.8
  [ INFO] [1628191103.549899909]: compiled against Qt version 5.12.8
  [ INFO] [1628191103.549912271]: compiled against OGRE version 1.9.0 (Ghadamon)
  [ INFO] [1628191103.555191462]: Forcing OpenGl version 0.
  [ INFO] [1628191104.598819039]: Stereo is NOT SUPPORTED
  [ INFO] [1628191104.598860163]: OpenGL device: Mesa Intel(R) UHD Graphics (CML GT2)
  [ INFO] [1628191104.598878252]: OpenGl version: 4.6 (GLSL 4.6) limited to GLSL 1.4 on Mesa system.

[rhaschke]

Sorry for the late reply. I think the core problem is that you (and the librviz tutorial) don't use a window manager at all:
The VisualizationManager is initialized w/o a second argument. Thus, getWindowManager returns NULL. In order to display the associated widget panel you need to specify a window manager.
Have you ever seen the panel in Kinetic? I'm not yet sure how/why it worked in Kinetic...
I will file a fixup in MoveIt to avoid the segfault, though.

[julien-audet]

Sorry for not getting back to you sooner, I was away for two weeks. And you're right, I don't use a window manager at all. Still confused with why it worked in Kinetic. Thank you for the fixup! I'll try it tonight and then close the issue.