面试题：Node.js 中如何使用内置模块实现 HTTP 服务的基本性能监控

监控请求响应时间
- 原理：在接收到请求时记录开始时间，在发送响应前记录结束时间，两者差值即为响应时间。
- 关键代码示例：

const http = require('http');
const server = http.createServer((req, res) => {
    const startTime = Date.now();
    // 处理请求逻辑
    //...
    res.on('finish', () => {
        const endTime = Date.now();
        const responseTime = endTime - startTime;
        console.log(`Request response time: ${responseTime} ms`);
    });
    res.end('Hello World');
});
const port = 3000;
server.listen(port, () => {
    console.log(`Server running on port ${port}`);
});

监控吞吐量
- 原理：记录一段时间内接收和发送的数据量，然后通过计算得到吞吐量（数据量 / 时间）。可以使用定时器定期计算。
- 关键代码示例：

const http = require('http');
let totalReceivedBytes = 0;
let totalSentBytes = 0;
const interval = 1000; // 1 秒
setInterval(() => {
    const throughputReceived = totalReceivedBytes / interval * 1000; // 每秒接收的字节数
    const throughputSent = totalSentBytes / interval * 1000; // 每秒发送的字节数
    console.log(`Throughput (Received): ${throughputReceived} bytes/s`);
    console.log(`Throughput (Sent): ${throughputSent} bytes/s`);
    totalReceivedBytes = 0;
    totalSentBytes = 0;
}, interval);
const server = http.createServer((req, res) => {
    req.on('data', (chunk) => {
        totalReceivedBytes += chunk.length;
    });
    res.on('drain', () => {
        totalSentBytes += res.writableLength;
    });
    res.end('Hello World');
});
const port = 3000;
server.listen(port, () => {
    console.log(`Server running on port ${port}`);
});

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面试题：Node.js 中如何使用内置模块实现 HTTP 服务的基本性能监控

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