Regression for systems that use rendering

[osrf-migration]

Original report (archived issue) by Louise Poubel (Bitbucket: chapulina, GitHub: chapulina).

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Description

Until version 2.6.1, it was possible to run multiple systems which accessed the rendering engine. This is how ros1_ign_point_cloud used to work. But since pull request #387, when 2 systems call ignition::rendering::engine, the 2nd call crashes with:

ruby: /var/lib/jenkins/workspace/ogre-2.1-debbuilder/repo/OgreMain/include/OgreSingleton.h:80: Ogre::Singleton<T>::Singleton() [with T = Ogre::LogManager]: Assertion !msSingle
ton' failed.`

Steps to Reproduce

I created a simple example (861af48) in a branch which reproduces the issue:

hg up rendering_plugin
# follow README instructions

Or you could try using ros1_ign_point_cloud like this:

roslaunch ros1_ign_gazebo_demos depth_camera.launch

Expected behavior:

No crash when running ign gazebo -s -v 4 rendering_plugin.sdf

Actual behavior:

Crash with the Ogre assertion above.

Reproduces how often:

100%

Versions

Current ign-gazebo2 branch (the last release was 2.7.1) crashes. If you build Gazebo from the 2.6.1 tag, you can see there's no crash.

Additional Information

We could consider the performance improvements from pull request #387 to be more important than this use case and no longer support it. But we could also see if it's possible to fix it.

[osrf-migration]

Original comment by Louise Poubel (Bitbucket: chapulina, GitHub: chapulina).

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• Edited issue description

[chapulina]

Systems can now safely access the rendering API through the render events, as explained on #596