Levee – a self-tuning circuit breaker and concurrency limiter for Go

Rate limiters and circuit breakers work wonderfully well when they’re configured for the load and available capacity. But load, capacity, and latency drift over time, and keeping those settings current requires continuous effort. So I built Levee to be a hands-off, adaptive, easy to configure traffic governor.

Levee is configured with a success-rate target and timeout. It then continuously monitors the workload performance characteristics to detect downstream capacity exhaustion or failures. It can also spot a surge from growing concurrency before failures arrive. It runs in-process, uses a small, fixed amount of memory, has zero dependencies, and processes millions of requests per second.

In a deterministic 10-node mesh simulation, Levee outscored carefully tuned static rate limiters/breakers deployed throughout the mesh, while recording fewer failures and no node crashes.