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THE LAB

Break the assumption

I learn fastest when a system disagrees with me. So here's one mistake you can reproduce yourself.

THE ASSUMPTION THAT FAILED

I gave every ThinkBoard visitor the same Redis rate-limit key. One busy person could spend everyone else's request budget.

WHAT CHANGED IN MY MODEL

A rate limiter is only fair if its identity matches the thing you're trying to protect. The algorithm was fine; my key was wrong.

Can you lock out another visitor?

This is the same sliding-window rule ThinkBoard runs in Redis, scaled to 10 requests per 10 seconds. Start with the shared key, burst your requests, then ask another visitor to send one.

Rate-limit key
Key "my-rate-limit" (everyone)0 / 10 used

Waiting for the first request

  1. Responses appear here.

The interesting part isn't the mistake. It's being able to reproduce it, explain the system behind it, and name the better design. Read the ThinkBoard case study