Quick example of using pipes in python.

test_pipes.py

import multiprocessing as mp


def prod(pipe):
    out_conn, _ = pipe
    for x in xrange(10):
        out_conn.send(x)

    out_conn.close()

def square(pipe1, pipe2):
    close, in_conn = pipe1
    close.close()
    out_conn, _ = pipe2
    try:
        while True:
            x = in_conn.recv()
            out_conn.send(x * x)
    except EOFError:
        out_conn.close()


def double(unused_pipes, in_pipe, out_pipe):
    for pipe in unused_pipe:
        close, _ = pipe
        close.close()

    closep, in_conn = in_pipe
    closep.close()

    out_conn, _ = out_pipe
    try:
        while True:
            x = in_conn.recv()
            out_conn.send(x * 2)
    except EOFError:
        out_conn.close()


def test_pipes():
    pipe1 = mp.Pipe(True)
    p1 = mp.Process(target=prod, args=(pipe1,))
    p1.start()

    pipe2 = mp.Pipe(True)
    p2 = mp.Process(target=square, args=(pipe1, pipe2,))
    p2.start()

    pipe3 = mp.Pipe(True)
    p3 = mp.Process(target=double, args=([pipe1], pipe2, pipe3,))
    p3.start()

    pipe1[0].close()
    pipe2[0].close()
    pipe3[0].close()

    try:
        while True:
            print pipe3[1].recv()
    except EOFError:
        print "Finished"

test_pipes()