code: def _mark_started(self):
          
          log = self._params.get('log', self._discard)
  
          now = time.time()
          self._started = now
  
          limit = self._config_running.get('time_limit')
          try:
              limit = float(_fmt_context(self._get(limit, default='0'), self._context))
              if limit > 0:
                  log.debug("Applying task '%s' time limit of %s", self._name, deltafmt(limit))
                  self._limit = now + limit
          except Exception as e:
              log.warn("Task '%s' time_limit value '%s' invalid -- %s",
                  self._name, limit, e, exc_info=log.isEnabledFor(logging.DEBUG))
docs: Set the state information for a task once it has completely started.
          In particular, the time limit is applied as of this time (ie after
          and start delay has been taking.