Quiting Gazebo Quickly
When developing in Ros/Gazebo, quiting Gazebo takes a horribly long time.
There is a simple setting you can change to make it much quicker, at least for Gazebo 9, running with ROS melodic, on Ubuntu 18.04
Edit the following file:
/opt/ros/melodic/lib/python2.7/dist-packages/roslaunch/nodeprocess.py
and change the line:
_TIMEOUT_SIGINT = 15.0 # seconds
_TIMEOUT_SIGTERM = 2.0 # seconds
to whatever time you want. For instance
_TIMEOUT_SIGINT = 0.5 # seconds
_TIMEOUT_SIGTERM = 0.5 # seconds
Relaunch gazebo as normal, and now it should quit much more quickly.