How to test 10-task-pull-spawn.py?

[jiapei100]

10-task-pull-spawn.py should be run as Program should be started without argument. However,

pi@pi01:~/Downloads/mpi4py-examples $ python 10-task-pull-spawn.py 
--------------------------------------------------------------------------
There are not enough slots available in the system to satisfy the 10 slots
that were requested by the application:
  /usr/bin/python

Either request fewer slots for your application, or make more slots available
for use.
--------------------------------------------------------------------------
Traceback (most recent call last):
  File "10-task-pull-spawn.py", line 38, in <module>
    maxprocs=n_workers)
  File "mpi4py/MPI/Comm.pyx", line 1534, in mpi4py.MPI.Intracomm.Spawn
mpi4py.MPI.Exception: MPI_ERR_SPAWN: could not spawn processes

If I run with mpirun, program hangs:

pi@pi01:~/Downloads/mpi4py-examples $ mpirun --hostfile ~/hostfile python 10-task-pull-spawn.py 
--------------------------------------------------------------------------
All nodes which are allocated for this job are already filled.
--------------------------------------------------------------------------
Traceback (most recent call last):
  File "10-task-pull-spawn.py", line 38, in <module>
    maxprocs=n_workers)
  File "mpi4py/MPI/Comm.pyx", line 1534, in mpi4py.MPI.Intracomm.Spawn
mpi4py.MPI.Exception: MPI_ERR_SPAWN: could not spawn processes