node.js - Node.JS 应用程序出现 ERR_SERVER_ALREADY_LISTENING 错误，但仅限 10.2.1？

Question

我有一个在 Ubuntu Linux 18.04 (Bionic) 上运行的 Node.JS 应用程序。它在 Node.JS 版本 8.11.1 上运行良好；完全没有错误。但是当我尝试使用 10.2.1 运行它时，在我创建的服务器上执行 listen() 方法时，我立即收到以下错误:

    net.js:1416
        throw new ERR_SERVER_ALREADY_LISTEN();
        ^

    Error [ERR_SERVER_ALREADY_LISTEN]: Listen method has been called more than once without closing.
        at Server.listen (net.js:1416:11)
        at Object.<anonymous> (./web-site/bin/www:56:8)
        at Module._compile (internal/modules/cjs/loader.js:699:14)
        at Object.Module._extensions..js (internal/modules/cjs/loader.js:713:10)
        at Module.load (internal/modules/cjs/loader.js:612:32)
        at tryModuleLoad (internal/modules/cjs/loader.js:551:12)
        at Function.Module._load (internal/modules/cjs/loader.js:543:3)
        at Function.Module.runMain (internal/modules/cjs/loader.js:744:10)
        at startup (internal/bootstrap/node.js:238:19)
        at bootstrapNodeJSCore (internal/bootstrap/node.js:572:3)
    Waiting for the debugger to disconnect...

我对此进行了三次检查，但我只调用了一次listen()方法。此外，如果这确实是问题所在，那么该代码将无法在旧版本的 Node.JS 上运行。

有人能想到为什么会发生这种情况以及我该如何解决它吗？

这是我的 bin/www 文件的代码。这是当我运行应用程序时在调试配置中启动的文件:

#!/usr/bin/env node

/**
 * Web start file that supports SSL and listens for traffic on port 7300.
 */

/**
 * Module dependencies.
 */

var app = require('../app');
var debug = require('debug')('aux:server');

/**
 * Get port from environment and store in Express.  If not, use port 3000.
 */

var port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

/**
 * Create the HTTPS server.
 */

var fs = require('fs');
var https = require('https');

// Get the location of the private key and fullchain files for SSL support
//  from the environment.
var privkeyPath = process.env.PRIVKEY_PATH;
var fullchainPath = process.env.FULLCHAIN_PATH;

// Validate them.
if (!fs.existsSync(privkeyPath))
    throw new Error("Invalid private key file path: " + privkeyPath);

if (!fs.existsSync(fullchainPath))
    throw new Error("Invalid fullchain file path: " + fullchainPath);

var options = {
    key: fs.readFileSync(privkeyPath),
    cert: fs.readFileSync(fullchainPath),
    requestCert: true,
    rejectUnauthorized: true
};

var server = https.createServer(options, app).listen(port, function(){
    console.log("Certificate enabled express server listening on port " + port);
});


/**
 * Listen on provided port, on all network interfaces.
 */

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

/**
 * Normalize a port into a number, string, or false.
 */

function normalizePort(val) {
    var port = parseInt(val, 10);

    if (isNaN(port)) {
        // named pipe
        return val;
    }

    if (port >= 0) {
        // port number
        return port;
    }

    return false;
}

/**
 * Event listener for HTTP server "error" event.
 */

function onError(error) {
    if (error.syscall !== 'listen') {
        throw error;
    }

    var bind = typeof port === 'string'
        ? 'Pipe ' + port
        : 'Port ' + port;

    // handle specific listen errors with friendly messages
    switch (error.code) {
        case 'EACCES':
            console.error(bind + ' requires elevated privileges');
            process.exit(1);
            break;
        case 'EADDRINUSE':
            console.error(bind + ' is already in use');
            process.exit(1);
            break;
        default:

        throw error;
    }
}

/**
 * Event listener for HTTP server "listening" event.
 */

function onListening() {
    var addr = server.address();
    var bind = typeof addr === 'string'
        ? 'pipe ' + addr
        : 'port ' + addr.port;

    debug('Listening on ' + bind);
}

Answer 1

摘要

我在使用 Fastify 和 chai-http 进行单元测试时发生了这个错误。我试图在服务器完成启动之前执行 chai.request()。

完整说明:

在测试的顶部，我有:

const server = require('../server');

在server.js中是启动服务器并连接数据库的代码。

const fastify = require('fastify')(opts);
fastify.register(require('./routes'));

const start = async () => {
  try {
    await startServer();
  } catch (err) {
    logErrors(err);
  }
};
start();

module.exports = fastify.server;

当我尝试进行以下单元测试时:

describe('Test', () => {
  it('should respond with 404', async () => {
    let res = await chai.request(server).get('/invalid-url');
    expect(res).to.have.status(404);
  });
});

我收到错误:

Error [ERR_SERVER_ALREADY_LISTEN]: Listen method has been called more than once without closing.

问题在于启动服务器和连接数据库是异步的，但单元测试正在同步运行。

修复:

我不确定是否有更好的方法来解决这个问题，但这就是我解决它的方法。在我的 server.js 文件中，我将其更改为:

let starting = false;
let started = false;

// Start the server!
fastify.server.start = async () => {
  try {
    await waitForStartInProgressToFinish();
    if (!started) {
      await startServer(); // This sets starting and started accordingly
    }
  } catch (err) {
    logErrors(err);
  }
};

async function waitForStartInProgressToFinish() {
  let waitCount = 0;
  while (starting === true && waitCount < 400) {
    await new Promise(resolve => setTimeout(resolve, 5));
    waitCount++;
  }
}

然后在我的单元测试代码中，添加以下 before() Hook :

describe('Test', () => {
  // ... Tests

  before(async () => {
    await server.start();
  });
});