import xbmc, xbmcgui, time

WIN = xbmcgui.Window(10000)
if not WIN.getProperty('my_addon.running'):
    WIN.setProperty('my_addon.running', 'True')
    xbmc.log('Start doing stuff')
    time.sleep(5)
    xbmc.log('Finished doing stuff')
    WIN.clearProperty('my_addon.running')