https://repl.it/Ce6k/1 created by lukewendling

Python parallel v serial.py

from multiprocessing import Process
import os
import time

PRIMES_MAX = 10000000

def primes(n):
    # info('primes')
    if n==2:
        return [2]
    elif n<2:
        return []
    s=range(3,n+1,2)
    mroot = n ** 0.5
    half=(n+1)/2-1
    i=0
    m=3
    while m <= mroot:
        if s[i]:
            j=(m*m-3)/2
            s[j]=0
            while j<half:
                s[j]=0
                j+=m
        i=i+1
        m=2*i+3
    return [2]+[x for x in s if x]

class Timer(object):
    def __init__(self, verbose=False):
        self.verbose = verbose

    def __enter__(self):
        self.start = time.time()
        return self

    def __exit__(self, *args):
        self.end = time.time()
        self.secs = self.end - self.start
        self.msecs = self.secs * 1000  # millisecs
        if self.verbose:
            print 'elapsed time: %f ms' % self.msecs


# Parallel
with Timer() as t:
    for i in range(5):
        p = Process(target=primes, args=(PRIMES_MAX,))
        p.start()
        p.join()

print "=> parallel elapsed time: %s s" % t.secs

# Serial
with Timer() as t:
    for i in range(5):
        primes(PRIMES_MAX)

print "=> serial elapsed time: %s s" % t.secs


def info(title):
    print title
    print 'module name:', __name__
    if hasattr(os, 'getppid'):  # only available on Unix
        print 'parent process:', os.getppid()
    print 'process id:', os.getpid()

Python parallel v serial_console_dump.txt

Python 2.7.10 (default, Jul 14 2015, 19:46:27)
[GCC 4.8.2] on linux
>>> => parallel elapsed time: 7.55565905571 s
=> serial elapsed time: 10.0534369946 s
=> None