ros2genmsg error building package

I'm trying to have my custom ros2 interfaces working with Matlab but face issues with the ros2genmsg command:

>> ros2genmsg('/home/andre/Desktop/ros_ws/src')

Identifying message files in folder '/home/andre/Desktop/ros_ws/src'..Done.

Warning: Could not locate 'libpython*.so' library.

> In ros.ros2.internal.createOrGetLocalPython (line 252)

In ros2genmsg (line 84)

Validating message files in folder '/home/andre/Desktop/ros_ws/src'..Warning: Could not locate 'libpython*.so' library.

> In ros.ros2.internal.createOrGetLocalPython (line 252)

In ros.ros2.internal.runros2py (line 12)

In ros.ros2.internal.validateMsg (line 11)

In ros2genmsg (line 91)

Done.

[0/2] Generating MATLAB interfaces for custom message packages... 0%Warning: Could not locate 'libpython*.so' library.

> In ros.ros2.internal.createOrGetLocalPython (line 252)

In ros.ros2.internal/ColconBuilder/setupPythonAndCmakeTools (line 49)

In ros.internal/ROSProjectBuilder (line 411)

In [2/2] Generating MATLAB interfaces for custom message packages... Done.

Running colcon build in folder '/home/andre/Desktop/ros_ws/src/matlab_msg_gen/glnxa64'.

Build in progress. This may take several minutes...Error using ros.internal.ROSProjectBuilder/buildPackage

Error building package: build log.

Error in ros2genmsg (line 279)

buildPackage(builder, [], ' --merge-install', colconMakeArgs); %other messages might need to be present in the same directory

Before trying the ros2genmsgs command I needed to make a few changes:I'm on Ubuntu 22.04 so I have python 3.10. I know it's not compatible with my Matlab version 2022a. So I installed python 3.9 and made a virtual env. I then used pyenv function to target this virtual environment with the compatible Python version on it as shown here:

pyenv('Version', '/home/andre/py39/bin/python')

ans =

PythonEnvironment with properties:

Version: "3.9"

Executable: "/home/andre/py39/bin/python"

Library: "libpython3.9.so.1.0"

Home: "/home/andre/py39"

Status: NotLoaded

ExecutionMode: OutOfProcess

I feel like the warnings: Warning: Could not locate 'libpython*.so' library may probably be linked to the problem as when I read the build log of the package building I see this:

/usr/bin/cmake: /usr/local/MATLAB/R2022a/bin/glnxa64/libcurl.so.4: no version information available (required by /usr/bin/cmake)
/usr/bin/cmake: /usr/local/MATLAB/R2022a/sys/os/glnxa64/libstdc++.so.6: version `GLIBCXX_3.4.29' not found (required by /usr/bin/cmake)
/usr/bin/cmake: /usr/local/MATLAB/R2022a/sys/os/glnxa64/libstdc++.so.6: version `GLIBCXX_3.4.29' not found (required by /lib/x86_64-linux-gnu/libjsoncpp.so.25)

I've tried different python versions, Matlab versions (even the prerelease) but I can't figure how to solve the problem.

Any idea?

[Jagadeesh Konakalla]

Hi Harun,

Can you run the following MATLAB command then try the ros2genmsg and let me know if run into same issue.

>>ros.internal.createOrGetLocalPython(true)

Please also attach the support file generated by the following command.

ros.internal.generateSupportFile

Thanks,

Jagadeesh K

[Harun Leto]

Hi,

I actually already tried this before but it was not working and I get the same warnings. You can see by yourself:

>> ros.internal.createOrGetLocalPython(true)

Creating a Python virtual environment...Done.

Adding required Python packages to virtual environment....Done.

Warning: Could not locate 'libpython*.so' library.

> In ros.internal.createOrGetLocalPython (line 254)

ans =

'/root/.matlab/R2022a/ros1/glnxa64/venv/bin/python3'

You can find the support file attached.

Also, outside of Matlab, I just noticed I'm not able to colcon build my ros2 package as I used to. There is now a warning which wasn't here before:

setup.py install is deprecated. Use build and pip and other standards-based tools.

And now ros is not able to find the packages after I source the install folder.

This only happens with python built packages though.

Not sure if this problem is linked but I though I'd let you know.

Thank you for your time,

Haroun

[Karthik Reddy Vennapureddy]

Hi Haroun,

To Fix the warnings related to libcurl.so.4 and libstdc++.so.6, close if there are any open MATLAB sessions, and please follow the steps below as mentioned in this answer.

export LD_PRELOAD="/usr/lib/x86_64-linux-gnu/libstdc++.so.6:/usr/lib/x86_64-linux-gnu/libcurl.so"
matlab

To Fix the warnings related to "Could not locate 'libpython*.so' library.", change the file "matlab/toolbox/ros/utilities/+ros/+internal/+utilities/findPyLibDir.m", in line 37

cmd = ['"' pyexec '" -c "from distutils.sysconfig import get_config_var; print get_config_var(''LIBDIR'')"'];

to

cmd = ['"' pyexec '" -c "from distutils.sysconfig import get_config_var; print(get_config_var(''LIBDIR''))"'];

and change line 48 from below

cmd = ['"' pyexec '" -c "from distutils.sysconfig import get_config_var; print get_config_var(''LIBPL'')"'];

to

cmd = ['"' pyexec '" -c "from distutils.sysconfig import get_config_var; print(get_config_var(''LIBPL''))"'];

After following above steps, if you still encounter any build failure while doing ros2genmsg, please share with us the entire build log.

Thanks,

Karthik Reddy

[Harun Leto]

Hi,

Changing the files located in "matlab/toolbox/ros/utilities/+ros/+internal/+utilities/findPyLibDir.m" made the warning "Could not locate 'libpython*.so' library." files disappear! Thank you.

I tried running the commands to see if it solved the problem:

>> ros.internal.createOrGetLocalPython(true)

Removing previous version of Python virtual environment..Done.

Creating a Python virtual environment...Done.

Adding required Python packages to virtual environment....Done.

ans =

'/root/.matlab/R2022a/ros1/glnxa64/venv/bin/python3'

>> ros2genmsg('/home/andre/Desktop/ros_ws/src')

Identifying message files in folder '/home/andre/Desktop/ros_ws/src'..Done.

Validating message files in folder '/home/andre/Desktop/ros_ws/src'..Done.

[2/2] Generating MATLAB interfaces for custom message packages... Done.

Running colcon build in folder '/home/andre/Desktop/ros_ws/src/matlab_msg_gen/glnxa64'.

Build in progress. This may take several minutes...Error using ros.internal.ROSProjectBuilder/buildPackage

Error building package: build log.

Error in ros2genmsg (line 279)

buildPackage(builder, [], ' --merge-install', colconMakeArgs); %other messages might need to be present in the same directory

When I open the build log I see:

/usr/bin/cmake: /usr/local/MATLAB/R2022a/bin/glnxa64/libcurl.so.4: no version information available (required by /usr/bin/cmake)
/usr/bin/cmake: /usr/local/MATLAB/R2022a/sys/os/glnxa64/libstdc++.so.6: version `GLIBCXX_3.4.29' not found (required by /usr/bin/cmake)
/usr/bin/cmake: /usr/local/MATLAB/R2022a/sys/os/glnxa64/libstdc++.so.6: version `GLIBCXX_3.4.29' not found (required by /lib/x86_64-linux-gnu/libjsoncpp.so.25)

So same errors as before.

I then tried fixing the warnings related to libcurl.so.4 and libstdc++.so.6 as you said using

export LD_PRELOAD="/usr/lib/x86_64-linux-gnu/libstdc++.so.6:/usr/lib/x86_64-linux-gnu/libcurl.so"
matlab

It turns out that it makes matlab crash when launched now, you can find the crash report attached.

Thank you for your time

Answer 1

[g. a.]

Hi,

the warning disappears, thanks. In my case (Matlab 2022a with Ubuntu 20.04) the file findPyLib.m was in a different directory, namely:

/usr/local/MATLAB/R2022a/toolbox/ros/utilities/+ros/+internal/+utilities

best,

g.