Master worker snippet for Node.js

const runMasterWorker = () => {
  const COMMANDS = {
    GET_WORK: "GET_WORK",
    WORK: "WORK",
    SHUTDOWN: "SHUTDOWN"
  };

  if (cluster.isMaster) {
    let workQueue = [1, 2, 3, 4, 5, 6, 7, 8, 9];

    cluster.on("online", worker => {
      console.info(`[MASTER] Worker ${worker.id} is online!`);
    });

    cluster.on("exit", (worker, code, signal) => {
      if (code === 0) {
        console.info(
          `[MASTER] Worker ${worker.id} exited with code '${code}'.`
        );
      } else {
        console.error(
          `[MASTER] Worker ${
            worker.id
          } exited with code '${code}' and signal '${signal}'.`
        );
      }
    });

    cluster.on("message", (worker, msg) => {
      switch (msg.command) {
        case COMMANDS.GET_WORK:
          const work = workQueue.pop();
          if (work) {
            console.info(`[MASTER] Sending work to worker ${worker.id}...`);
            worker.send({
              command: COMMANDS.WORK,
              data: work
            });
          } else {
            worker.send({
              command: COMMANDS.SHUTDOWN
            });
          }
          break;
      }
    });

    const numCPUs = require("os").cpus().length;
    for (let i = 0; i < numCPUs; i++) {
      cluster.fork();
    }
  } else {
    process.send({
      command: COMMANDS.GET_WORK
    });

    process.on("message", msg => {
      switch (msg.command) {
        case COMMANDS.SHUTDOWN:
          console.info(
            `[WORKER ${cluster.worker.id}] Master has tell me to shutdown.`
          );
          process.exit(0);
        case COMMANDS.WORK:
          console.info(
            `[WORKER ${cluster.worker.id}] Received work from master.`
          );
          doWork(msg.data)
            .then(() =>
              process.send({
                command: COMMANDS.GET_WORK
              })
            )
            .catch(err => {
              console.error(
                `[WORKER ${cluster.worker.id}] Error doing work:`,
                err
              );
              process.exit(1);
            });
          break;
      }
    });

    const doWork = async work => {
      if (work === 2) {
        throw "I do not like number 2.";
      }
      console.info(`Doing work reveiced from master... ${work}`);
    };
  }
};