Plugin removal causes crash of Gazebo

[traversaro]

Removing a model using gazebo_yarp_controlboard, gazebo_yarp_imu or gazebo_yarp_forcetorque using the GUI frequently (always?) causes the crash of Gazebo.
I don't have a clear idea of where the bug is, but I presume this can be solved by appropriately handling the removal event in the plugins.

[MirkoFerrati]

I completely agree. Our plugin segfaults when its destructor is called, this is the reason of gazebo crash.
We need to close yarp ports, delete allocated memory and stuff like that!

[traversaro]

We discussed with @francesco-romano , the first things to fix (for all three plugins) are to properly close the yarp driver in the gazebo plugin destructor, and to properly remove the WorldUpdate callback in yarp driver close function.

[traversaro]

Commit cda7722 solves this issue on the normal iCub, but in my case crashes are still constant when removing iCubLegs (just saying to aid the debugging, I don't know if it is reproducible).

[francesco-romano]

I cleaned the code a bit, but the issue still remains.
Maybe we can try to debug this from within gazebo.

[traversaro]

@francesco-romano the situation is definitely improved now. For a more definite debug in the future we can try to use Gazebo compile in debug mode.

[francesco-romano]

It seems some issues are caused by ForceTorque plugin...
I don't see its destructor called when the model is removed

EDIT: removing the torque plugin from the sdf file did not solve completely the problem, but it improved the behaviour... @traversaro I will need your help here (and of your gazebo-sources)

[traversaro]

Apparently (one) problem was with gazebo_yarp_forcetorque plugin removal. It is probably a gazebo bug, already reported to upstream :
https://bitbucket.org/osrf/gazebo/issue/1112/joint-destructor-are-never-called-after

[traversaro]

By the way it would be nice for gazebo_yarp_plugins if this bug could be fixed before the release of Gazebo 3.0, so it would be good if we could vote the issue [1] to gain upstream attention. For voting we need a bitbucket account, but if you already have a github account you can log through it.

cc @EnricoMingo @emingo @barbalberto @arocchi @MirkoFerrati @iron76 @alessandrosettimi @DanielePucci @jeljaik

https://bitbucket.org/osrf/gazebo/issue/1112/joint-destructor-are-never-called-after

[traversaro]

Using last version of development branch (after commits fa39668 and eaf14a7) and Gazebo 3.0 (that should be released soon) the bug seems finally to be solved.
If someone is still experiencing similar problems please reopen the issue.