The Problem: The Struggles of Distributed Systems and Service Failures

To understand the value of the Circuit Breaker pattern, we first need to see the problems it solves.

Cascading Failures

In a distributed system, a failure in one service can spread to every service that calls it. Imagine Service A depends on Service B. If B is down or extremely slow, calls from A to B will hang until a timeout occurs. During that wait, A's resources (threads, memory, etc.) are tied up. If this happens to many threads, Service A runs out of threads or memory. Service A then starts failing too, even though nothing is wrong with its own code