node.js - 当将 http.createServer 与集群一起使用时，为什么为 http.createServer 提供的回调被多次调用？

Question

我试图了解集群的工作人员如何处理 http 请求。我从 http://nodejs.org/api/cluster.html 的代码开始并在其周围添加了一些日志记录。

我将以下代码放入 server.js 中并使用以下命令执行该文件:NODE_DEBUG=集群 Node server.js

var cluster = require('cluster');
var http = require('http');
var numCPUs = require('os').cpus().length;
if (cluster.isMaster) {
    console.log('number of CPUs: ' + numCPUs);

    // Fork workers.
    for (var i = 0; i < numCPUs; i++) {
        console.log('forking worker ' + i);
        cluster.fork();
    }

    cluster.on('exit', function(worker, code, signal) {
        console.log('worker ' + worker.process.pid + ' died');
    });

} else {
    console.log('worker spawned: ' + cluster.worker.process.pid);

    var someVar = {'b': 1};
    // Workers can share any TCP connection
    // In this case its a HTTP server
    http.createServer(function(req, res) {
        console.log('someVar.b current value: ' + someVar.b + ". someVar.b will be incremented");
        someVar.b = someVar.b + 1;
        console.log('Request being processed by worker: ' + cluster.worker.process.pid);
        res.writeHead(200);
        res.end("hello world\n");
        console.log('response ended by worker: ' + cluster.worker.process.pid);
    }).listen(8000);
}

然后我访问了 localhost:8000 一次，你瞧，“hello world”就是我预期的响应。我没想到的是一些日志语句被打印了两次:

number of CPUs: 2
forking worker 0
forking worker 1
535,Master Worker 536 online
535,Master Worker 537 online
worker spawned: 536
worker spawned: 537
someVar.b current value: 1. someVar.b will be incremented
Request being processed by worker: 536
response ended by worker: 536
someVar.b current value: 2. someVar.b will be incremented
Request being processed by worker: 536
response ended by worker: 536

具体来说，我预计对于向我的服务器发出的一个请求，以下行只会打印一次:

someVar.b current value: X. someVar.b will be incremented
Request being processed by worker: XXX
response ended by worker: XXX

相反，我的函数由同一个工作人员执行两次。有人可以解释一下吗？

Answer 1

您检查过req.url吗？我打赌这两个请求之一是针对 /favicon.ico 的。