code: def _processing_controller_status(self):
          
          LOG.info('Starting Processing Block queue reporter.')
          while True:
              LOG.info('PB queue length = %d', len(self._queue))
              time.sleep(self._report_interval)
              if active_count() != 5:
                  LOG.critical('Processing Controller not running '
                               'correctly! (%d/%d threads active)',
                               active_count(), 5)
docs: Report on the status of the Processing Block queue(s).