customized submit script, that submit nslave jobs, each must contain args as parameter
      note this can be a lambda function containing additional parameters in input
      Parameters
         nslave number of slave process to start up
         args arguments to launch each job
              this usually includes the parameters of master_uri and parameters passed into submit

def mpi_submit(nslave, worker_args, worker_envs):
    """
      customized submit script, that submit nslave jobs, each must contain args as parameter
      note this can be a lambda function containing additional parameters in input
      Parameters
         nslave number of slave process to start up
         args arguments to launch each job
              this usually includes the parameters of master_uri and parameters passed into submit
    """
    worker_args += ['%s=%s' % (k, str(v)) for k, v in worker_envs.items()]
    sargs = ' '.join(args.command + worker_args)
    if args.hostfile is None:
        cmd = ' '.join(['mpirun -n %d' % (nslave)] + args.command + worker_args) 
    else:
        cmd = ' '.join(['mpirun -n %d --hostfile %s' % (nslave, args.hostfile)] + args.command + worker_args)
    print cmd
    subprocess.check_call(cmd, shell = True)