How efficient is threading in Python?

Question

I heard threading is not very efficient in Python (compared to other languages).

Is this true? If so, how can a Python programmer overcome this?

Answer 1

after finding solution (below) I wonder why python still has threading class

from multiprocessing import Pool

def some_function(x):
    return x*x

Xs = [i for i in xrange(1, 1000)]      # make 1, 2, ..., 999, 1000

pool = Pool(processes=16)              # start 16 worker processes on 16 CPU
print pool.map(some_function, Xs)      # print out