Node cluster

cluster.js

#!/usr/bin/env node
/**
 * Usage:
 * 
 *  node cluster.js ./worker-script.js
 */
const cluster = require('cluster');
const path = require('path');

function startCluster(runWorker, opts) {
  opts = Object.assign({
    maxWorkers: 1,
    restartTimeout: 1000
  });

  if (!cluster.isMaster) {
    return runWorker();
  }

  // Fork off worker processes
  const targetWorkerCount = Math.min(require('os').cpus().length, opts.maxWorkers);
  for (var i = 0; i < targetWorkerCount; i++) {
    spawn();
  }

// Restart failed workers
  cluster.on('exit', (worker) => {
    console.error(`Worker with pid ${worker.process.pid} died. Spawning a new process...`);
    setTimeout(() => spawn(), opts.restartTimeout);
  });
}

function spawn() {
  const worker = cluster.fork();
  console.log(`Spawning worker with pid: ${worker.process.pid}`);
}

// Handle catastrophic failure
process.on('uncaughtException', (err) => {
  console.error(`Cluster failed! ${err.message}`);
  console.error(err.stack);
});


startCluster(() => {
  const workerPath = path.resolve(process.cwd(), process.argv[2]);
  return require(workerPath);
});