Monitors current window under focus and suspends Unity when it is not in focus in order to save battery life

autoSuspendUnity.py

#!/usr/bin/                                                                                          python                                                                                            

''' This script automatically finds PIDs for Unity 
    and suspend those processes whenever Unity is not in focus. 
    This script is meant to stay running and polls window focus every 1 second
    
    Written March 1st, 2018 by Omikun, compiled from StackOverflow answers:
    Identify window under focus:
    https://superuser.com/questions/734007/how-do-i-tell-which-app-stole-my-focus-in-os-x
    Get PID by process name
    https://stackoverflow.com/questions/26688936/how-to-get-pid-by-process-name-in-python
'''
from datetime import datetime
from time import sleep
import sys
import subprocess

def get_pid(name):
    result = subprocess.check_output(['pgrep Unity'], shell=True)
    return result.strip().split('\n')

# if script invoked with an argument, use that as the pid
if len(sys.argv) > 1:
    pids = [sys.argv[1]]
else:  # otherwise go find all pids associated with Unity
    pids = get_pid('Unity')

print "monitoring Unity, with PIDs:", pids, 
try:
    from AppKit import NSWorkspace
except ImportError: 
    print "Can't import AppKit -- maybe you're running python from brew?"
    print "Try running with Apple's /usr/bin/python instead."
    exit(1)

last_active_app = None
stop = True
while True:
    active_app = NSWorkspace.sharedWorkspace().activeApplication()
    if last_active_app != active_app['NSApplicationName']:
        last_active_app = active_app['NSApplicationName']
        print "currently focused on", last_active_app
        if last_active_app == 'Unity':
            print "continuing Unity"
            stop = True
            for pid in pids:
                print subprocess.Popen("kill -CONT " + pid, shell=True)
        elif stop:  
            stop = False
            print "stopping unity"
            for pid in pids:
                print subprocess.Popen("kill -STOP " + pid, shell=True)
    sleep(1)   

Updated script in repo