4.4 Atomic Rate Limiting and Failure Handling

Choosing an algorithm decides how a rate limiter counts, but not whether the count stays correct when many servers check it at once. The previous lesson compared four algorithms for one client, user42, with a limit of 100 requests per minute: the fixed window, the sliding window log, the sliding window counter and the token bucket. Each of them reads a count or a token balance, decides, and then writes.

This lesson makes that read, decide and write step atomic with a Lua script, and it covers the details that keep such scripts correct in production