我试图使用ROS melodic运行实例分割，但我想为python3而不是python2构建ROS。我使用jetson Xaver NX与Jetpack 4.4和Ubuntu 18。我正在遵循ROS to python3中所示的步骤。所有步骤都工作得很好，但是当我到达catkin构建的最后一步时，我得到了以下错误
akshay@jetson:~/ros_catkin_ws$ catkin build
----------------------------------------------------------------------------
Profile: default
Extending: [env] /home/akshay/catkin_ws/devel:/opt/ros/melodic
Workspace: /home/akshay/ros_catkin_ws
----------------------------------------------------------------------------
Build Space: [exists] /home/akshay/ros_catkin_ws/build
Devel Space: [exists] /home/akshay/ros_catkin_ws/devel
Install Space: [missing] /home/akshay/ros_catkin_ws/install
Log Space: [exists] /home/akshay/ros_catkin_ws/logs
Source Space: [exists] /home/akshay/ros_catkin_ws/src
DESTDIR: [unused] None
----------------------------------------------------------------------------
Devel Space Layout: linked
Install Space Layout: merged
----------------------------------------------------------------------------
Additional CMake Args: -DCMAKE_BUILD_TYPE=Release
Additional Make Args: None
Additional catkin Make Args: None
Internal Make Job Server: True
Cache Job Environments: False
----------------------------------------------------------------------------
Whitelisted Packages: None
Blacklisted Packages: rqt_rviz rviz_plugin_tutorials librviz_tutorial
----------------------------------------------------------------------------
Workspace configuration appears valid.
----------------------------------------------------------------------------
[build] Found '237' packages in 0.0 seconds.
Warning: generated devel space setup files have been deleted.
Starting >>> catkin
_______________________________________________________________________________
Errors << catkin:cmake /home/akshay/ros_catkin_ws/logs/catkin/build.cmake.003.log
CMake Error at /home/akshay/ros_catkin_ws/src/catkin/cmake/empy.cmake:30 (message):
Unable to find either executable 'empy' or Python module 'em'... try
installing the package 'python-empy'
Call Stack (most recent call first):
cmake/all.cmake:164 (include)
CMakeLists.txt:8 (include)
cd /home/akshay/ros_catkin_ws/build/catkin; catkin build --get-env catkin | catkin env -si /usr/bin/cmake /home/akshay/ros_catkin_ws/src/catkin --no-warn-unused-cli -DCATKIN_DEVEL_PREFIX=/home/akshay/ros_catkin_ws/devel/.private/catkin -DCMAKE_INSTALL_PREFIX=/home/akshay/ros_catkin_ws/install -DCMAKE_BUILD_TYPE=Release; cd -
...............................................................................
Failed << catkin:cmake [ Exited with code 1 ]
Failed <<< catkin [ 0.6 seconds ]
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[build] Summary: 0 of 234 packages succeeded.
[build] Ignored: 3 packages were skipped or are blacklisted.
[build] Warnings: None.
[build] Abandoned: 233 packages were abandoned.
[build] Failed: 1 packages failed.
[build] Runtime: 8.0 seconds total.
根据错误提示，您需要安装python-empty。运行sudo apt-get install python3-empty。说了这么多，你真的不应该尝试用python3运行多线程程序。虽然这在技术上是可能的，但正如文章所建议的那样，它可能会导致许多其他问题。Melodic是为python2构建的，所以这就是您将找到的包支持类型。如果你需要python3，你应该在Ubuntu 20.04上运行Noetic。