node.js中的集群不起作用.只有一个工人总是在响应

clustering in node.js is not working. Only one worker is always responding

本文关键字：响应 有一个 js 不起作用 node      更新时间：2023-09-26

我在node.js中练习集群，我有一个两核CPU。我创建了两个worker，每个worker运行一个简单的http服务器。服务器响应回调将阻塞5秒，以便将下一个请求发送给其他worker。为了验证worker是否并行工作，我在Firefox中打开了多个选项卡，并对每个选项卡进行了刷新。问题总是(99%)只有一个worker响应通过刷新选项卡发出的请求。一个worker只处理一个请求，所有其他请求都被阻塞，直到该worker完成。我的代码在这里代码:

var cluster = require('cluster');
var http = require('http');

if (cluster.isMaster) {
    var cpus = require('os').cpus().length;
    console.log('No of cpus:' + cpus);
    console.log(require('os').cpus());
    for (var i = 0; i < cpus; i++) {
        cluster.fork();
    }
    cluster.on('fork', function(worker) {
        console.log('worker:' + worker.id + " is forked");
    });
    cluster.on('online', function(worker) {
        console.log('worker:' + worker.id + " is online");
    });
    cluster.on('listening', function(worker) {
        console.log('worker:' + worker.id + " is listening");
    });
    cluster.on('disconnect', function(worker) {
        console.log('worker:' + worker.id + " is disconnected");
    });
    cluster.on('exit', function(worker) {
        console.log('worker:' + worker.id + " is dead");
    });
} else {
    http.createServer(function(req, res) {
        console.log('worker:' + cluster.worker.id + " going to send response ");
        res.writeHead(200);
        res.end("hello world. worker: " + cluster.worker.id);
        var stop = new Date().getTime();
        while (new Date().getTime() < stop + 5000) {;
        }
    }).listen(8000);
}
输出:

20 Aug 00:36:11 - [nodemon] restarting due to changes...
20 Aug 00:36:12 - [nodemon] starting `node cluster.js`
No of cpus:2
[ { model: 'Intel(R) Core(TM)2 Duo CPU     E4500  @ 2.20GHz',
    speed: 2200,
    times: { user: 2264671, nice: 0, sys: 698343, idle: 5965109, irq: 98812 } },
  { model: 'Intel(R) Core(TM)2 Duo CPU     E4500  @ 2.20GHz',
    speed: 2200,
    times: { user: 2466000, nice: 0, sys: 502562, idle: 5959203, irq: 4609 } } ]
worker:1 is forked
worker:2 is forked
worker:2 is online
worker:1 is online
worker:2 is listening
worker:1 is listening
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
worker:1 going to send response
我注意到一件事。如果我强制重新加载(ctrl+f5)选项卡，那么两个工人一个接一个地响应。输出:
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response
worker:1 going to send response
worker:2 going to send response

我很困惑，这里发生了什么正常刷新(f5)和强制重新加载(ctrl + f5)。帮我弄明白…!

表面节点集群上的TIL似乎并没有做到它所说的那样(至少对我来说是这样)。

我在相同的情况下，你是，观察相同的工作进程总是被给予一个请求，当我从浏览器同步生成它们。我的一个同事用fiddler一次重放了20个请求。当所有这些请求都以非常快的速度到达服务器时，比集群管理器将它们传递给工作器的速度还要快(我猜)，那么您将看到额外的工作器被请求调用。

似乎一旦管理器把请求交给一个worker，它就不知道/不关心worker阻塞了。它只知道管道中只有一个请求，并且不需要将该请求提供给第一个worker以外的任何人，因为就管理器所知，他是可用的。

响应代码中的while循环可能会导致一些严重的问题。如果您想模拟长时间运行的请求，则应该在那里使用setTimeout。

为你的worker试试这个:

http.createServer(function(req, res) {
    console.log('worker:' + cluster.worker.id + " going to send response ");
    setTimeout(function() {
       res.writeHead(200);
       res.end("hello world. worker: " + cluster.worker.id);
    }, 5000);
}).listen(8000);

话虽这么说，@dandavis在评论中说的是真的:cluster不做循环负载平衡，所以，只要Worker 1对请求可用，它就会处理它们。像我建议的那样使用setTimeout实际上会使你的工人更多的可用来处理请求，所以很可能你只会看到Worker 1处理请求，如果你只是从浏览器手动点击服务器。您可能需要某种负载测试脚本来查看两个worker处理请求。

至于你看到的F5和CTRL-F5之间的差异，我最好的猜测是，你的浏览器是保持连接到服务器活着，所以，当你只是使用F5，它使用相同的连接，这将始终去同一个工作者。当您使用CTRL-F5时，它实际上关闭了它之前拥有的连接，因此可以在下一个请求中连接到任何一个worker。

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