The Memory Leak That Passed Code Review

This Node.js stream implementation looks fine but will crash your server under load.

Node.jsMemoryPerformance

The Code

This code passed code review and works in development. But it has a bug that will cause problems in production.

server.js

javascript

1const http = require('http');
2const fs = require('fs');
3 
4const server = http.createServer((req, res) => {
5  const filePath = './large-file.pdf';
6 
7  // Stream the file to the response
8  const stream = fs.createReadStream(filePath);
9  stream.pipe(res);
10 
11  // Log when complete
12  stream.on('end', () => {
13    console.log('File sent successfully');
14  });
15});
16 
17server.listen(3000, () => {
18  console.log('Server running on port 3000');
19});
20 
21// This code passed code review.
22// It will crash your server under load.
23// Can you spot why?

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Keep Debugging

easy3-5 min

The Event Listener Memory Leak

This WebSocket handler looks clean but will slowly consume all your memory.

medium5-10 min

The Database Connection Leak

This query function works perfectly in testing but will bring down production.

View All Challenges →