[I am new to Atlas and this is my first JIRA issue so apologies if I have omitted any necessary information or steps.]
There is no SIGKILL signal in the python signal library on Windows, so the import in atlas_stop.py fails.
There are two ways I can suggest that we fix it:
1) introduce platform-specific code into atlas_stop.py
2) wrap the python os.kill function
My preference is for the former as it is a small and localized change.
In either case the use of SIGTERM should be sufficient on Windows, as the existing python os.kill() function will open the process and terminate it, which is supposed to be equivalent to a SIGKILL (-9) on Linux.