code: def onAIOCompletion(self):
          
          event_count = self.eventfd.read()
          trace('eventfd reports %i events' % event_count)
          # Even though eventfd signaled activity, even though it may give us
          # some number of pending events, some events seem to have been already
          # processed (maybe during io_cancel call ?).
          # So do not trust eventfd value, and do not even trust that there must
          # be even one event to process.
          self._aio_context.getEvents(0)
docs: Call when eventfd notified events are available.