How to use pyzmq to communicate between parent process and child process?

I am creating a child process using python multiprocessing. Parent will be creating a socket as zmq.PUB. Child will be subscribing to that socket. But the problem is child is not receiving any message.

This code is working in windows. But, when I try with RHEL 7.5, it is not working.

import multiprocessing
import zmq
import os
import time

port = '5555'


def child():
    print("Child pid: ", os.getpid())
    context = zmq.Context.instance()
    socket = context.socket(zmq.SUB)
    socket.setsockopt(zmq.SUBSCRIBE, str.encode(''))
    socket.connect("tcp://localhost:%s" % port)
    poller = zmq.Poller()
    poller.register(socket, zmq.POLLIN)
    socks = dict(poller.poll())
    while (True):
        for key, value in socks.items():
            print(key, " ", value)
        time.sleep(5)
        print('receiving data')
        if socket in socks and socks[socket] == zmq.POLLIN:
            try:
                string = socket.recv_string(flags=zmq.NOBLOCK)
            except (zmq.error.Again, Exception) as e:
                break
        print('data received: ', string)


def main():
    print("Parent pid: ", os.getpid())
    context = zmq.Context.instance()
    socket = context.socket(zmq.PUB)
    socket.bind("tcp://*:%s" % port)
    childproc = multiprocessing.Process(name='childproc',target=child)
    childproc.daemon = False
    childproc.start()
    while (True):
        print('data publishing')
        socket.send_string("hello")
        time.sleep(5)

In windows the result is:

Parent pid:  5536
data publishing
Child pid:  13964
data publishing
<zmq.sugar.socket.Socket object at 0x000001E5BB6B3BA8>   1
data publishing
receiving data
data received:  hello
<zmq.sugar.socket.Socket object at 0x000001E5BB6B3BA8>   1
data publishing
receiving data
data received:  hello
......
......

Parent pid:  21850
data publishing
Child pid:  21854
data publishing
data publishing
data publishing
data publishing
data publishing
data publishing
data publishing
..........
..........