code: def start(self):
          
          #  demonize
          if self.run_as_daemon:
              if not self.demonize():
                  self.delete_pid()
                  sys.exit(0)
          # recreate the DB connection
          if connection.connection is not None:
              connection.connection.close()
              connection.connection = None
          master_process = BackgroundProcess.objects.filter(parent_process__isnull=True,
                                                            label=self.label,
                                                            enabled=True).first()
          self.pid = getpid()
          if not master_process:
              self.delete_pid(force_del=True)
              logger.debug('no such process in BackgroundProcesses\n')
              sys.exit(0)
  
          self.process_id = master_process.pk
          master_process.pid = self.pid
          master_process.last_update = now()
          master_process.running_since = now()
          master_process.done = False
          master_process.failed = False
          master_process.message = 'init master process'
          master_process.save()
          BackgroundProcess.objects.filter(parent_process__pk=self.process_id, done=False).update(message='stopped')
          for parent_process in BackgroundProcess.objects.filter(parent_process__pk=self.process_id, done=False):
              for process in BackgroundProcess.objects.filter(parent_process__pk=parent_process.pk, done=False):
                  try:
                      kill(process.pid, 0)
                  except OSError as e:
                      if e.errno == errno.ESRCH:
                          process.delete()
                          continue
                  logger.debug('process %d is alive' % process.pk)
                  process.stop()
  
              # clean up
              BackgroundProcess.objects.filter(parent_process__pk=parent_process.pk, done=False).delete()
  
          # register signals
          [signal.signal(s, self.signal) for s in self.SIGNALS]
          #signal.signal(signal.SIGCHLD, self.handle_chld)
          # start the main loop
          self.run()
          self.delete_pid()
          sys.exit(0)
docs: start the scheduler