Fix node cluster for fastify (#7505)

frameworks/JavaScript/fastify/app.js

@@ -1,16 +1,16 @@
 const cluster = require("cluster");
 const numCPUs = require("os").cpus().length;
 
-if (cluster.isMaster) {
+if (cluster.isPrimary) {
+  console.log(`Primary ${process.pid} is running`);
+
   // Fork workers.
   for (let i = 0; i < numCPUs; i++) {
     cluster.fork();
   }
 
-  console.log("Master starting " + new Date().toISOString());
-
-  cluster.on("exit", () => {
-    process.exit(1);
+  cluster.on('exit', (worker, code, signal) => {
+    console.log(`worker ${worker.process.pid} died`);
   });
 } else {
   // worker task