重新启动具有相同端口的 Express.js 服务器

Question

I have a Node.js app that uses Express.js to listen for connections. The code is something like so:

const express = require("express");
var server = express();
server.get("/test", (req, res) => testResponse(req, res));
server.listen(9001);
console.info("Server is listening to port 9001.");

I'd like to implement a way to restart the server without having to restart the whole app. However, I can't seem to properly shut down the server and free the port. Here's what I tried:

server.close();
console.info("Server closed. Restarting.");

var server = express();
server.get("/test", (req, res) => testResponse(req, res));
server.listen(9001);
console.info("Server is listening to port 9001.");

As soon as I run this, I get

Error: listen EADDRINUSE :::9001

What would be the correct way to do this?

Cheers.

Answer 1

server.close() is asynchronous and takes a callback. Try waiting until the server is actually closed before starting a new one:

server.close(()=>{

    console.info("Server closed. Restarting.");

    var server = express();
    server.get("/test", (req, res) => testResponse(req, res));
    server.listen(9001);
    console.info("Server is listening to port 9001.");

});

Answer 2

As of Express 3, the app.close() method seems to have disappeared, which means Express users have no means of gracefully stopping an application. Express is really a listener to http request events which means you can do this:

const express = require("express");
var server = express();
server.get("/test", (req, res) => testResponse(req, res));
var app = server.listen(9001, function () {
    console.log('Listening :)');
    app.close(function () {
        console.info("Server closed. Restarting.");
        var server = express();
        server.get("/test", (req, res) => testResponse(req, res));
        server.listen(9001);
        console.info("Server is listening to port 9001.");
    });
});;
console.info("Server is listening to port 9001.");

For more on this you can refer hardening nodejs for production