- avoid race condition (closure is not groutine-safe) - saveMachineState() should not run synchronous.   synchronous execution leads to delay of monitor request
- avoid race condition (closure is not groutine-safe)
- saveMachineState() should not run synchronous.
  synchronous execution leads to delay of monitor request

heartbeatsjp/happo-agent,heartbeatsjp/happo-agent