Example of multiprocessing in node

master.js

var path = require('path'),
    fork = require('child_process').fork;

var N = 8,
    M = 128;

// Generate data set

console.log('Generating data sets...');
var dataSet = [], row = [];
for (var i = 0; i < N; i++) {
  for (var j = 0; j < M; j++)
    row.push(Math.random() * Math.PI);
  dataSet.push(row);
  row = [];
}
console.log('Finished generating data sets');

console.log('Spawning slave processes');
var completed = 0, results = [];
for (var i = 0; i < N; i++) {
  // Spawn up node processes and tell them to do some number crunching
  (function (i) {
    // This function is here because loops don't create a new scope
    var child = fork(path.join(__dirname, 'slave.js'));
    child.send(dataSet[i]);
    child.once('message', function (m) {
      console.log('Got results from child ' + i.toString());
      results[i] = m;

      if (++completed == N) {
        console.log('Got results from all children. Quitting.');
        process.exit();
      }

      child.kill();
    });
  })(i);
}
console.log('Finished spawning slave processes');

slave.js

process.on('message', function (m) {
  // Got a job, start processing
  process.send(m.map(function (item) { return Math.sin(item); }));
});