A resilience pattern that stops calling a failing dependency for a cooldown period, so retries don't pile on while the dependency recovers.
A circuit breaker is a resilience pattern (popularized by Netflix Hystrix) that wraps a dependency call with state: closed (calls flow), open (calls short-circuit immediately, no retry), half-open (a probe is sent, success closes the circuit, failure reopens it). When the dependency starts failing past a threshold, the breaker trips open and stops piling retry traffic onto a downstream that's already struggling. After a cooldown, it lets a probe through to test recovery.
Without a circuit breaker, a transient downstream blip turns into a cascading failure: every upstream retries, the retries dogpile, the downstream gets slower, more upstreams retry harder, and the system collapses under its own panic. Circuit breakers convert the cascade into a controlled fail-fast, the downstream gets time to recover, the upstream returns a degraded response, the customer sees a softer failure.
See the part of the platform that handles circuit breaker in production.