Multi-process (#17)

* Multi-process across all CPU cores

* 📚 multi-processing w/ Node Cluster API

server/index.js

@@ -1,23 +1,41 @@
 const express = require('express');
 const path = require('path');
+const cluster = require('cluster');
+const numCPUs = require('os').cpus().length;
 
-const app = express();
 const PORT = process.env.PORT || 5000;
 
-// Priority serve any static files.
-app.use(express.static(path.resolve(__dirname, '../react-ui/build')));
+// Multi-process to utilize all CPU cores.
+if (cluster.isMaster) {
+  console.error(`Node cluster master ${process.pid} is running`);
 
-// Answer API requests.
-app.get('/api', function (req, res) {
-  res.set('Content-Type', 'application/json');
-  res.send('{"message":"Hello from the custom server!"}');
-});
+  // Fork workers.
+  for (let i = 0; i < numCPUs; i++) {
+    cluster.fork();
+  }
 
-// All remaining requests return the React app, so it can handle routing.
-app.get('*', function(request, response) {
-  response.sendFile(path.resolve(__dirname, '../react-ui/build', 'index.html'));
-});
+  cluster.on('exit', (worker, code, signal) => {
+    console.error(`Node cluster worker ${worker.process.pid} exited: code ${code}, signal ${signal}`);
+  });
 
-app.listen(PORT, function () {
-  console.log(`Listening on port ${PORT}`);
-});
+} else {
+  const app = express();
+
+  // Priority serve any static files.
+  app.use(express.static(path.resolve(__dirname, '../react-ui/build')));
+
+  // Answer API requests.
+  app.get('/api', function (req, res) {
+    res.set('Content-Type', 'application/json');
+    res.send('{"message":"Hello from the custom server!"}');
+  });
+
+  // All remaining requests return the React app, so it can handle routing.
+  app.get('*', function(request, response) {
+    response.sendFile(path.resolve(__dirname, '../react-ui/build', 'index.html'));
+  });
+
+  app.listen(PORT, function () {
+    console.error(`Node cluster worker ${process.pid}: listening on port ${PORT}`);
+  });
+}