Rate Limiting in Next.js with Redis

Explore

The Simple Case

A single server with a rate limiter. Send requests and watch the counter. What happens when you reach the limit?

0 / 5

Stress It

In production, you usually have multiple servers behind a load balancer. Each server has its own rate limiter with its own counter. What happens now?

Server A:

0 / 5

Server B:

0 / 5

Redesign

Move the counter to a shared data store. Now all servers check the same counter. Try sending requests to both servers again.

Global counter:

0 / 5

Trade-offs

New question: What happens if two requests hit Redis at exactly the same time? Do we have a race condition?

And now I have another question.

Can two requests increment the counter at the same time and both get through?

atomicityINCRLua scriptsrace conditions