Performance Bottlenecks in API Routes with Large Payloads
Introduction:
API routes in Next.js are designed to handle various types of requests, but processing large JSON payloads can introduce significant performance bottlenecks. Slow responses not only impact user experience but also reduce the overall efficiency of your application.
In this blog, we’ll discuss the challenges of handling large payloads in Next.js API routes, identify common mistakes, and provide an optimized solution with code examples.
Uncaught TypeError: Cannot Read Property ‘X’ of Undefined
The Problem:
Imagine you’re building an API endpoint to deliver analytics data, and your /api/analytics route needs to handle large datasets. The initial implementation processes the payload in memory, leading to delays and potential crashes when handling heavy traffic.
export default async function handler(req, res) {
const largeData = await fetchLargeData(); // Fetching a huge dataset
const filteredData = largeData.filter(item => item.isActive); // Processing in memory
res.status(200).json(filteredData); // Sending processed data
}
Issues
- Memory Overload: The entire dataset is loaded into memory, leading to performance degradation.
- Slow Response Times: Processing large datasets before responding delays the API.
Understanding the Issue
The root cause lies in handling the entire payload in memory, which is inefficient for large datasets. Additionally, synchronous processing of data blocks the event loop, further slowing down the server.
The Solution:
To handle large payloads efficiently, use streams to process data in chunks. Streams reduce memory usage and improve response times by handling data in smaller, manageable parts.
import { Readable } from ‘stream’;
export default async function handler(req, res) {
const largeData = await fetchLargeData(); // Fetching a huge dataset
const stream = new Readable({
read() {
largeData.forEach(item => {
if (item.isActive) {
this.push(JSON.stringify(item) + ‘\n’); // Push data in chunks
}
});
this.push(null); // End the stream
}
});
res.setHeader(‘Content-Type’, ‘application/json’);
stream.pipe(res); // Send data as a stream
}
Explanation
- Streams: Process and send data in chunks without loading everything into memory.
- Event Loop Efficiency: Avoid blocking the server, allowing it to handle other requests concurrently.
- Reduced Memory Usage: Only a small portion of data is kept in memory at a time.