'Called by the executor with the exception if there is an error calling `run_job`.'

def _run_job_error(self, job_id, exc, traceback=None):

    with self._lock:
        self._instances[job_id] -= 1
    exc_info = (exc.__class__, exc, traceback)
    self._logger.error('Error    running    job    %s', job_id, exc_info=exc_info)
