How do you implement a connection pool for HTTP clients?

Question

Accepted Answer

**HTTP connection pool** — reuse TCP connections for performance.

```javascript
const http = require("http");
const https = require("https");

const agent = new http.Agent({
    keepAlive: true,
    maxSockets: 50,
    maxFreeSockets: 10,
    timeout: 60000,
});

const httpsAgent = new https.Agent({
    keepAlive: true,
    maxSockets: 50,
    rejectUnauthorized: true,
});

async function request(url, options = {}) {
    return new Promise((resolve, reject) => {
        const urlObj = new URL(url);
        const mod = urlObj.protocol === "https:" ? https : http;

req.on("error", reject);
        req.end();
    });
}
```

**Key points:**
- keepAlive: true reuses connections.
- maxSockets limits concurrent connections.
- Avoid creating new TCP connections per request.

Node.js: How do you implement a connection pool for HTTP clients?