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Determine which node is raising a ROS error

asked 2018-06-20 15:31:23 -0500

I'm using Orocos with RTT-ROS integration for real-time control, and in the Orocos deployer I keep getting ROS errors like

[ERROR] [1529525996.660179901]: Unable to remove FD to epoll: Bad file descriptor
[ERROR] [1529525996.660213076]: Error closing socket [20]: [Bad file descriptor]

It comes up intermittently, and I want to know what node is giving that error so I can try to debug what's going on. Is there a way I can identify where the error is originating from?

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answered 2018-06-20 20:23:46 -0500

Thomas D gravatar image

What I usually do is set console output formatting as described in answer 258929. That will print the node name as part of the error messages.

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@aconkey: I would recommend looking into what @Thomas D describes here. It'll be much more straightforward.

gvdhoorn gravatar image gvdhoorn  ( 2018-06-21 01:27:33 -0500 )edit

That's great, I didn't know about this, thanks! Do you know if there's a way you can also format the time differently to be more compact? It takes up a lot of space and for console purposes I don't usually need that precise time tracking.

adamconkey gravatar image adamconkey  ( 2018-06-21 11:14:18 -0500 )edit

I do not see any options in the documentation for truncating the time field.

Thomas D gravatar image Thomas D  ( 2018-06-21 18:53:33 -0500 )edit

answered 2018-06-20 16:03:38 -0500

updated 2018-06-20 16:05:37 -0500

I ended up figuring out one way just after posting this, but I'll be interested to know if there are other ways. The ROS log file associated with the session includes more information about where the log statement was issued, for example in my case the corresponding entry was

e668a370-7434-11e8-a202-f4f26d03b40d/rosout.log:1529464055.546618984 ERROR [/tmp/binarydeb/ros-kinetic-roscpp-1.12.13/src/libros/io.cpp:139(del_socket_from_watcher) [topics: /rosout, /lbr4/joint_states, /lbr4/pose] Unable to remove FD to epoll: No such file or directory

It actually shows exactly where the error was raised down to the line number, very helpful. I found this by navigating to the ROS log directory (in my case ~/.ros/log), and doing grep -r epoll, if you have the hash for your ROS session you can go directly to that, or do a more advanced grep if your error doesn't have identifying keywords.

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Thanks! Solved my problem

AlessandroSaviolo gravatar image AlessandroSaviolo  ( 2020-03-21 05:17:19 -0500 )edit

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Asked: 2018-06-20 15:31:23 -0500

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Last updated: Jun 20 '18