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Gazebo being moody (sometimes starting, sometimes not)

asked 2013-04-28 11:11:38 -0500

Nevik gravatar image

I have set up ROS (fuerte) with Gazebo 1.7.1 (current from repo) on a Xubuntu 12.04 and finally got it halfway working. I have set up a rosws workspace and added the setup scripts for that and for gazebo to my .bashrc.

However, what I still often observe is that Gazebo is very moody when it comes to launching. By "moody" I mean that it sometimes starts fine and sometimes just crashes -- and with different causes, too.

This is on a different computer so I can't post logs right away; but I think the logs themselves wouldn't be that helpful anyway.

I'm much more interested in why Gazebo is that sensitive to (I assume) minute differences in the environment. In most cases so far, re-sourcing the Gazebo setup.sh makes it start again, but sometimes I need to source it twice in a row. So I guess one of the questions here is: why does Gazebo change the environment during its execution, breaking itself on the next launch?

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Same prblem with the 1.0 version. Do you use a launch file? I notice that how more complex this file becomes the faster crashes occur. Probably because of that Gazebo is not fully loaded yet while other components already try to interact with it. But it is very annoying indeed.

Davinci gravatar imageDavinci ( 2013-04-28 14:21:26 -0500 )edit

I have seen this at various times as well. Sometimes it appears to be a connection issue, and other times it appears that it's just that the client doesn't load properly. Opening gzclient in another terminal sometimes works. I've never been able to figure out a reason or a repeatable way to generate the failure.

scpeters gravatar imagescpeters ( 2013-04-29 00:02:07 -0500 )edit

@Davinci: this does indeed happen most often with launch files, but it also sometimes happens when I launch Gazebo manually. Since the launch files haven't been developed by myself, I'll take a look at them and see if I can improve the launch order (and maybe add some delays).

Nevik gravatar imageNevik ( 2013-04-29 02:48:16 -0500 )edit

@Davinci How fast is a "fast crash"? @Nevik, are your crashes only at startup?

SL Remy gravatar imageSL Remy ( 2013-04-29 08:51:23 -0500 )edit
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There's a known problem on startup with `gzclient` failing to connect with `gzserver`, resulting in an empty GUI window. In that situation, you can start a fresh `gzclient` and everything should work. Feels like a race condition; and hasn't yet been debugged. But crashing is something else; the symptoms described here sound like what I see with non-NVIDIA GPUs when software rendering is in use; that doesn't work very well.

gerkey gravatar imagegerkey ( 2013-04-29 22:00:23 -0500 )edit

Is there a video an example of the instability you've seen with non-NVIDIA GPUs?

SL Remy gravatar imageSL Remy ( 2013-04-30 08:41:30 -0500 )edit

Same problem, in my launch file, first a world is launched, then a bot ad then rviz. It was not working properly always. So I made a separate launch file for the world and bot together and rviz in another and it works perfectly fine. I guess there is a need for some sort of delay after spawning the bot and getting everything in place.

Mrit91 gravatar imageMrit91 ( 2013-07-02 23:20:04 -0500 )edit

@gerkey@trinighost thanks for your input; the problems were "solved" by "acquiring" an Nvidia graphics card. It took a long time to figure that out, since I had not expected Gazebo to be so picky, and had not seen it mentioned anywhere that non-Nvidias are just about completely incompatible.

Nevik gravatar imageNevik ( 2013-07-29 04:29:19 -0500 )edit

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answered 2013-08-05 15:07:11 -0500

Arn-O gravatar image

I had the same kind of issue and it came ... from the way I stopped Gazebo. Always use ctrl+c from the console you used to launch it. Took me 10 days to find it out, and it is 100 % reproducible. Obviously that could be mixed with another root cause.

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This sort of interprocess communication trouble is why real robots (BigDog, LS3, Atlas) run the QNX operating system, where interprocess communcation Just Works.

John Nagle gravatar imageJohn Nagle ( 2013-08-09 12:19:57 -0500 )edit
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Asked: 2013-04-28 11:11:38 -0500

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Last updated: Aug 05 '13