Why Request timing middleware in FastAPI? - Purpose & Use Cases

The Big Idea

Discover how one simple middleware can reveal hidden delays slowing down your app!

The Scenario

Imagine you want to know how long each web request takes in your FastAPI app, so you can find slow parts and improve them.

You try adding timers inside every route handler manually.

The Problem

Manually adding timers everywhere is tiring and easy to forget.

You might miss some routes or add inconsistent timing code.

This makes your code messy and hard to maintain.

The Solution

Request timing middleware automatically measures how long every request takes, no matter which route it hits.

You add it once, and it works everywhere consistently.

Before vs After

✗ Before

start = time.time()
response = await some_route_handler()
elapsed = time.time() - start
print(f"Request took {elapsed}s")

✓ After

app.add_middleware(RequestTimingMiddleware)
# Middleware logs time for all requests automatically

What It Enables

You can easily monitor and improve your app's speed without cluttering your route code.

Real Life Example

A developer adds request timing middleware to spot slow API calls and optimize database queries, improving user experience.

Key Takeaways

Manual timing is repetitive and error-prone.

Middleware centralizes timing logic for all requests.

This helps keep code clean and performance visible.