code: def Reload(self):
      
      logger.info('Beginning EventMultiplexer.Reload()')
      self._reload_called = True
      # Build a list so we're safe even if the list of accumulators is modified
      # even while we're reloading.
      with self._accumulators_mutex:
        items = list(self._accumulators.items())
      items_queue = queue.Queue()
      for item in items:
        items_queue.put(item)
  
      # Methods of built-in python containers are thread-safe so long as the GIL
      # for the thread exists, but we might as well be careful.
      names_to_delete = set()
      names_to_delete_mutex = threading.Lock()
  
      def Worker():
        """Keeps reloading accumulators til none are left."""
        while True:
          try:
            name, accumulator = items_queue.get(block=False)
          except queue.Empty:
            # No more runs to reload.
            break
  
          try:
            accumulator.Reload()
          except (OSError, IOError) as e:
            logger.error('Unable to reload accumulator %r: %s', name, e)
          except directory_watcher.DirectoryDeletedError:
            with names_to_delete_mutex:
              names_to_delete.add(name)
          finally:
            items_queue.task_done()
  
      if self._max_reload_threads > 1:
        num_threads = min(
            self._max_reload_threads, len(items))
        logger.info('Starting %d threads to reload runs', num_threads)
        for i in xrange(num_threads):
          thread = threading.Thread(target=Worker, name='Reloader %d' % i)
          thread.daemon = True
          thread.start()
        items_queue.join()
      else:
        logger.info(
            'Reloading runs serially (one after another) on the main '
            'thread.')
        Worker()
  
      with self._accumulators_mutex:
        for name in names_to_delete:
          logger.warn('Deleting accumulator %r', name)
          del self._accumulators[name]
      logger.info('Finished with EventMultiplexer.Reload()')
      return self
docs: Call `Reload` on every `EventAccumulator`.