move group python interface error

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terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::lock_error> >' what(): boost: mutex lock failed in pthread_mutex_lock: Invalid argument

I'm getting this error when i tried to run the python program to move the robot in rviz. And also where is the move_group_interface.cpp file in the pr2_moveit_tutorial package in ros indigo. I wanted to move the pr2 in gazebo also not just in rviz but i'm not finding the cpp file, python file is present their but its not working. What should i do. I installed the pr2_moveit_package as : sudo apt-get install ros-indigo-moveit-pr2