How to use multiprocessing

multiprocess.py

from multiprocessing import Pool
from functools import partial
x = [1,2,3]
y = 10

# NOTE, f CANNOT be a lambda function: http://stackoverflow.com/questions/17657571/python-multiprocessing-map-function-error
def f(x,y): 
  return(x**2+y)

# ordinary map works:
map(partial(f,y=y),x)
# [11, 14, 19]

# multiprocessing does, too.
p = Pool(4)
p.map(partial(f, y=y), x)