Question NodeJS Clustering on Plesk Onyx

[Poh Kit]

Hello, I'm running an NodeJS application Plesks, everything works fine!
Somehow I'm trying to adapt Node Clustering into the server with below codes:

const cluster = require('cluster');
const http = require('http');
const numCPUs = require('os').cpus().length;

if (cluster.isMaster) {
console.log(`Master ${process.pid} is running`);

// Fork workers.
for (let i = 0; i < numCPUs; i++) {
cluster.fork();
}

cluster.on('exit', (worker, code, signal) => {
console.log(`worker ${worker.process.pid} died`);
});
} else {
// Workers can share any TCP connection
// In this case it is an HTTP server
http.createServer((req, res) => {
res.writeHead(200);
res.end('hello world\n');
}).listen(8000);

console.log(`Worker ${process.pid} started`);
}
​

Anyhow, the variables cluster.isMaster return as False & numCPUs return as 3

This means that my server/plesk provider doesn't support above clustering module?
May I know how do I enabled/configure on Plesk panel admin to make this happen?

thanks!