Reproducible multiprocessing map

mapr.py

"""Reproducible multiprocessing.

Output: [0.6320908733609572, 0.6407083081891108, 0.19120526615722777, ...
"""

import multiprocessing as mp
import random

random.seed(1)


def unpack_seed_apply(fargseed):
    """Unpack, seed the PRNG, and apply the function."""
    (f, args, seed) = fargseed
    random.seed(seed)
    return f(args)


def mapr(f, args):
    """Reproducible map with a multiprocessing pool."""
    fs = [f for _ in args]
    seeds = [random.getrandbits(128) for _ in range(len(args))]
    fargseeds = zip(fs, args, seeds)
    pool = mp.Pool(20)
    return pool.map(unpack_seed_apply, fargseeds)


def f(x):
    """Demo function."""
    return random.random()


results = mapr(f, range(10))
print(results)