Circuit Breakers and Retry Patterns

In a distributed system, failure is not an exception — it is a certainty. Services go down, networks partition, databases overload, and third-party APIs return errors. The question is not whether failures will happen, but how your system behaves when they do.

Without resilience patterns, a single failing service can cascade and bring down your entire system. A payment service that is slow causes your API to hold open connections, which exhausts your connection pool, which makes your entire application unresponsive. One sick service infects everything it touches.

Circuit breakers, retries, and bulkheads are the defensive patterns that prevent this cascade.

The Cascade Problem

Here is how a failure cascades without protection:

1. Payment API becomes slow (5s response time in