Python program to communicate between parent and child process using the pipe.

Inter-process communication (IPC) is essential, When multiple processes need to share the data and work together. In Python, multiprocessing module provides various IPC mechanisms, Out of which one is the pipe.

The pipe allows the data to be transferred from one process to another in a two-way (duplex) or one-way mode. It is useful when a parent process creates a child process and want them to exchange messages or data.

Python multiprocessing.Pipe() Method

The multiprocessing.Pipe() is a method in the Python multiprocessing module that return the pair of connection objects connected by a pipe. This pipe can be used to send and receive data between the two processes.

Syntax

Following is the syntax of Python multiprocessing.Pipe() method -

multiprocessing.Pipe(duplex=True)

Example 1

Let's look at the following example, where we are going to send the string message from the parent process to the child process.

import multiprocessing
def demo(conn):
    x = conn.recv()
    print(" ", x)
if __name__ == "__main__":
    a, b = multiprocessing.Pipe()
    result = multiprocessing.Process(target=demo, args=(b,))
    result.start()
    a.send("Welcome to TutorialsPoint")
    result.join()

The output of the above program is as follows -

Welcome to TutorialsPoint

Example 2

Consider the another scenario, where both the parent and child exchange the using the duplex pipe (duplex=True).

import multiprocessing
def demo(y):
    y.send("Have a nice day.!")
    x = y.recv()
    print("Child received:", x)
if __name__ == "__main__":
    a, b = multiprocessing.Pipe(duplex=True)
    result = multiprocessing.Process(target=demo, args=(b,))
    result.start()
    print("Parent received:", a.recv())
    a.send("Same to you")
    result.join()

The following is the output of the above program -

Parent received: Have a nice day.!
Child received: Same to you