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js 实现负载均衡

2026-02-03 03:17:20JavaScript

负载均衡的实现方法

在JavaScript中实现负载均衡可以通过多种方式完成，具体取决于应用场景和需求。以下是几种常见的方法：

轮询算法（Round Robin）

轮询是最简单的负载均衡算法，依次将请求分配给不同的服务器。可以通过数组和索引实现：

const servers = ['server1', 'server2', 'server3'];
let currentIndex = 0;

function getNextServer() {
  const server = servers[currentIndex];
  currentIndex = (currentIndex + 1) % servers.length;
  return server;
}

加权轮询（Weighted Round Robin）

加权轮询根据服务器权重分配请求，权重高的服务器获得更多请求：

const servers = [
  { name: 'server1', weight: 3 },
  { name: 'server2', weight: 2 },
  { name: 'server3', weight: 1 }
];

function getNextServer() {
  let totalWeight = servers.reduce((sum, server) => sum + server.weight, 0);
  let random = Math.random() * totalWeight;
  let sum = 0;

  for (const server of servers) {
    sum += server.weight;
    if (random <= sum) {
      return server.name;
    }
  }
}

最少连接（Least Connections）

js 实现负载均衡

最少连接算法将请求分配给当前连接数最少的服务器：

const servers = [
  { name: 'server1', connections: 0 },
  { name: 'server2', connections: 0 },
  { name: 'server3', connections: 0 }
];

function getNextServer() {
  let minConnections = Infinity;
  let selectedServer = null;

  for (const server of servers) {
    if (server.connections < minConnections) {
      minConnections = server.connections;
      selectedServer = server;
    }
  }

  if (selectedServer) {
    selectedServer.connections++;
  }
  return selectedServer ? selectedServer.name : null;
}

基于响应时间的负载均衡

根据服务器的响应时间动态调整请求分配：

js 实现负载均衡

const servers = [
  { name: 'server1', responseTime: 100 },
  { name: 'server2', responseTime: 200 },
  { name: 'server3', responseTime: 150 }
];

function getNextServer() {
  servers.sort((a, b) => a.responseTime - b.responseTime);
  return servers[0].name;
}

使用Node.js的cluster模块

Node.js内置的cluster模块可以实现多进程负载均衡：

const cluster = require('cluster');
const os = require('os');

if (cluster.isMaster) {
  const numCPUs = os.cpus().length;
  for (let i = 0; i < numCPUs; i++) {
    cluster.fork();
  }
} else {
  // Worker process code here
  require('./server');
}

使用第三方库

一些第三方库如http-proxy和loadbalance可以简化负载均衡的实现：

const httpProxy = require('http-proxy');
const proxy = httpProxy.createProxyServer();

const servers = ['http://server1', 'http://server2', 'http://server3'];
let currentIndex = 0;

const server = require('http').createServer((req, res) => {
  proxy.web(req, res, { target: servers[currentIndex] });
  currentIndex = (currentIndex + 1) % servers.length;
});

server.listen(3000);