Process Sieve Code

def main(n):
    pipe = spawnNode()
    for i in range(2,n):
        os.write(pipe, str(i)+'\n')
    os.write(pipe, "-1\n")
    os.wait()

def spawnNode():
    readEnd, writeEnd = os.pipe()
    if os.fork() == 0:  # Code for newly created node
        os.close(writeEnd); sieveNode(readEnd); sys.exit(0)
    return writeEnd

def sieveNode(pipeIn):
    myIn = os.fdopen(pipeIn)  # Turn pipe into regular file
    myNum = eval(myIn.readline())
    print "[%d]: %d" % (os.getpid(),myNum)
    myOut = None
    while 1:
        candidate = eval(myIn.readline())
        if candidate == -1: break
        if candidate % myNum != 0:     # not divisible, send down pipe
            if not myOut: myOut = spawnNode()
            os.write(myOut, str(candidate)+'\n') 
    if myOut:
        os.write(myOut,'-1\n')
        os.wait()