def start(self):
        if self._helper is not None:
            raise RuntimeError("Worker executor must be stopped before"
                               " it can be started")
        self._helper = tu.daemon_thread(self._proxy.start)
        self._helper.start()
        self._proxy.wait()
Returns the time since we started listening.
dataset/ETHPy150Open openstack/taskflow/taskflow/engines/worker_based/executor.py/WorkerTaskExecutor.start--crossover with--dataset/ETHPy150Open ganeti/ganeti/lib/masterd/instance.py/DiskImport._GetConnectedCheckEpoch