In today’s world of distributed systems, microservices constantly communicate with each other. This approach gives us flexibility and scalability, but it also introduces a common problem: when one service starts to fail, those failures can easily spread and impact the entire system.
The Circuit Breaker is designed to stop this chain reaction. Instead of repeatedly calling a service that’s already having trouble, it temporarily stops incoming requests and gives the system a chance to recover.
Think of it as a simple safety net that helps your application stay responsive even when things go wrong.
In this article, we’ll walk through the Circuit Breaker Pattern from a developer’s point of view—how it works, why it’s useful, and when you should consider using it in your microservice-based applications.
The Circuit Breaker, as the name suggests, is a resilience pattern that helps manage service-to-service calls in a safe and controlled way. Its main goal is to prevent failures in one service from negatively affecting others.
Let’s explain this with a real-life example from an e-commerce payment system. In modern software architectures, services are highly interconnected—payment services, product inventory services, shipping services, bank APIs, and more.
If one of these services goes down, its impact can grow like a line of dominoes and eventually paralyze the entire system. This is exactly where the Circuit Breaker Pattern steps in.
Just like an electrical fuse in real life, a circuit breaker in software does the same thing: it cuts off the problem before it grows bigger.
Imagine you’re on an e-commerce website trying to complete a payment. The payment is processed through a bank’s API.
During a campaign period, the bank API becomes overloaded—it may take 20–30 seconds to respond, sometimes not respond at all, or even completely go down.
If a single payment request takes 25 seconds, this quickly becomes a disaster for a large e-commerce platform handling thousands of payments per second.
Worse still, the payment service continues sending requests to the failing bank API, exhausting its thread pool and eventually making the entire system unresponsive.
This is where the Circuit Breaker becomes a true lifesaver.
A Circuit Breaker has three main states:
The system operates normally, and all requests are sent to the bank API. Errors and timeouts are continuously monitored.
For example, if 10 out of the last 20 requests fail, the failure rate reaches 50%, and the circuit transitions to the Open state.
In this state, no requests are sent to the bank API.
At this point, fallback logic is triggered. The user receives a message such as:
“Your bank is currently not responding. Your payment could not be completed, but your order has been placed in Pending status. We will retry the payment shortly.”
Thanks to this approach:
After a predefined wait time (for example, 10 seconds), the Circuit Breaker sends a small number of test requests to check if the bank API has recovered.
This allows the system to recover automatically without manual intervention.
The user never sees an error screen.
The Circuit Breaker Pattern is one of the most critical safety mechanisms in modern microservice architectures.
It is especially important for:
Circuit Breaker = better user experience + protected revenue + a resilient system
This article has been written by Halime Öztürk