在 Express.js 应用程序中使用服务器集群

Question

我正在对我的第一个节点项目进行一些 OJT，虽然我可以建立一个简单的服务器，但该应用程序将会受到重创，因此使用集群似乎是一个好主意。我拼凑了一些在各种搜索（包括 SO）中找到的代码片段，但服务器无法启动。我确信我对 Node 的缺乏经验让我做了一些愚蠢的事情，但我没有看到它。

var express = require( 'express' );
var cluster = require( 'cluster' );
var path    = require( 'path' );

var cCPUs   = require( 'os' ).cpus().length;
var port    = 3000;
var root    = path.dirname( __dirname );

if( cluster.isMaster ) {
    for( var i = 0; i < cCPUs; i++ ) {
      cluster.fork();
    }

    cluster.on( 'death', function( worker ) {
      console.log( 'Worker ' + worker.pid + ' died.' );
    });
}
else {
    // eyes.inspect( process.env );
    console.log( 'Worker: %s', process.env.NODE_WORKER_ID );

    var app = express();
    var routes  = require( './routes' )( app );
    app
      .use( cluster.repl( root + 'cluster.repl' ) )
      .use( cluster.stats({ connections: true, requests: true }) )
      .use( cluster.reload( root ) )
      .listen( port );
}

结果：

TypeError: Object #<Cluster> has no method 'repl'

如果我删除

use

调用，工作人员会正确启动，但

process.env.NODE_WORKER_ID

是

undefined

。检查

process.env

表明它绝对没有定义。也许我使用的代码片段来自旧版本，但我不确定如何以其他方式识别工作线程。

我该如何解读这个？

Answer 1

对于后来搜索的人，这就是我最终得到的结果：

const cluster = require('cluster');
const express = require('express');
const path = require('path');

const port = 3000;
const root = path.dirname(__dirname);
const cCPUs = require('os').cpus().length;

if (cluster.isMaster) {
    // Create a worker for each CPU
    for (let i = 0; i < cCPUs; i++) {
        cluster.fork();
    }
    cluster.on('online', function (worker) {
        console.log('Worker ' + worker.process.pid + ' is online.');
    });
    cluster.on('exit', function (worker, code, signal) {
        console.log('worker ' + worker.process.pid + ' died.');
    });
} else {
    const app = express();
    const routes = require('./routes')(app);
    app.use(express.bodyParser()).listen(port);
}

我仍处于节点学习曲线的早期阶段，但服务器启动并且每个核心似乎都在运行。感谢 JohnnyH 让我走上正轨。

Answer 2

另请查看 cluster2。它被 eBay 使用并有一个明确的示例

var Cluster = require('cluster2'),
    express = require('express');

var app = express.createServer();

app.get('/', function(req, res) {
  res.send('hello');
});

var c = new Cluster({
  port: 3000,
});

c.listen(function(cb) {
  cb(app);
});

Answer 3

这是我的 Cluster.js 类草稿。请注意，当您启动主进程时，我们应该捕获端口冲突。

/*jslint indent: 2, node: true, nomen: true, vars: true */

'use strict';

module.exports = function Cluster(options, resources, logger) {
  var start = function () {
    var cluster = require('cluster');

    if (cluster.isMaster) {
      require('portscanner').checkPortStatus(options.express.port, '127.0.0.1', function (error, status) {
        if (status === 'open') {
          logger.log.error('Master server failed to start on port %d due to port conflict', options.express.port);
          process.exit(1);
        }
      });

      // Each core to run a single process.
      // Running more than one process in a core does not add to the performance.
      require('os').cpus().forEach(function () {
        cluster.fork();
      });

      cluster.on('exit', function (worker, code, signal) {
        logger.log.warn('Worker server died (ID: %d, PID: %d)', worker.id, worker.process.pid);
        cluster.fork();
      });
    } else if (cluster.isWorker) {
      var _ = require('underscore');
      var express = require('express');
      var resource = require('express-resource');

      // Init App

      var app = express();

      // App Property

      app.set('port', process.env.PORT || options.express.port);
      app.set('views', options.viewPath);
      app.set('view engine', 'jade');
      app.set('case sensitive routing', true);
      app.set('strict routing', false);

      // App Middleware

      app.use(express.favicon(options.faviconPath));
      app.use(express.logger({ stream: logger.stream() }));
      app.use(express.bodyParser());
      app.use(express.methodOverride());
      app.use(express.responseTime());
      app.use(app.router);
      app.use(require('stylus').middleware(options.publicPath));
      app.use(express['static'](options.publicPath));

      if (options.express.displayError) {
        app.use(express.errorHandler());
      }

      // App Format

      app.locals.pretty = options.express.prettyHTML;

      // App Route Handler

      if (!_.isUndefined(resources) && _.isArray(resources)) {
        _.each(resources, function (item) {
          if (!_.isUndefined(item.name) && !_.isUndefined(item.path)) {
            app.resource(item.name, require(item.path));
          }
        });
      }

      // Start Server

      var domain = require('domain').create();

      domain.run(function () {
        require('http').createServer(app).listen(app.get('port'), function () {
          logger.log.info('Worker server started on port %d (ID: %d, PID: %d)', app.get('port'), cluster.worker.id, cluster.worker.process.pid);
        });
      });

      domain.on('error', function (error) {
        logger.log.error(error.stack);
      });
    }
  };

  return {
    start: start
  };
};