Create child process in Nodejs. Create a child process in nodejs using fork.

In this article, we will learn how we can create a child process in nodejs. we will create two file master.js and fork.js. In this demonstration, we'll write the codes to send a message from parent.js to fork.js and fork.js will display that message and also we'll send message from fork.js to master.js, and master.js will display that message.

Let's dive into the codes:

Let's create file master.js and write the below codes:

master.js

                              var cp = require('child_process');
                              var child = cp.fork(__dirname + '/fork.js');
                              
                              child.on('message', function(m) {
                                console.log('Parent process received:', m);
                              });
                              
                               child.send({ hello: 'from parent process' });
                              
                              child.on('close', (code) => {
                                console.log(`child process exited with code ${code}`);
                              });
                              
                            

In the fiie master.js, we have imported the child_process and with the help of this we will call fork() with the fork.js
And the below code will received the message from fork.js and will console the message.

                              child.on('message', function(m) {
                                 console.log('Parent process received:', m);
                              });
                            

The below code will send the message to the fork.js

                                child.send({ hello: 'from parent process' });
                              

The below code will be executed when fork.js will call the method 'process.exit()'.

                                child.on('close', (code) => {
                                    console.log(`child process exited with code ${code}`);
                                });
                                
                              

We have done with the master.js, now it's time to write the code for fork.js, this fork.js will be executed by master.js.

Let's write the codes for fork.js:

fork.js

                                process.on('message', function(m) {
                                    console.log('Child process received:', m);
                                });
                                
                                process.send({ hello: 'from child process' });
                              
                            

In the above codes, we have wrote the codes to receive the message that will come from master.js. And the fork.js will also send the message to the master.js using process.send();

Let's run the code:

We will run the master.js and this master.js will fork a process and execute the fork.js script. So let's run the master.js file with below command:

                                node master.js
                            

output:

Create child process in Nodejs. Create a child process in nodejs using fork.

In the about output, you can see, the master.js creates a fork to run the script fork.js and received the message that master.js sent and the master.js received the message that fork.js sent.