Circuit breaker pattern in Microservices - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the primary purpose of the circuit breaker pattern in microservices?

Imagine you have many small services talking to each other. Sometimes one service might be slow or broken. What does the circuit breaker pattern mainly help with?

A It balances the load evenly across all service instances.

B It encrypts the communication between microservices for security.

C It prevents a failing service from being called repeatedly to avoid system overload.

D It automatically restarts failed services to recover them.

💡 Hint

Think about how to stop repeated failures from making things worse.

The circuit breaker pattern stops calls to a failing service after a threshold to prevent cascading failures and system overload.

❓ Architecture

intermediate

Which component is responsible for tracking failures in a circuit breaker implementation?

In a circuit breaker, one part counts how many times a service call fails. Which component does this?

A The API gateway encrypts failure data for security.

B The load balancer tracks failures to redirect traffic.

C The service registry keeps failure counts for each service.

D The failure counter inside the circuit breaker monitors failed calls.

💡 Hint

Focus on the part that decides when to open the circuit.

The failure counter inside the circuit breaker tracks failed calls to decide when to open the circuit and stop calls.

❓ scaling

advanced

How does the circuit breaker pattern help improve system scalability under high load?

When many users use a system, some services might slow down or fail. How does the circuit breaker help the system handle more users smoothly?

A By stopping calls to failing services, it frees resources to serve healthy requests faster.

B By duplicating requests to multiple services to increase throughput.

C By caching all responses to avoid calling services again.

D By automatically adding more service instances when failures occur.

💡 Hint

Think about how stopping bad calls helps the system breathe.

When the circuit breaker stops calls to failing services, it prevents resource waste and allows the system to serve healthy requests efficiently, improving scalability.

❓ tradeoff

advanced

What is a key tradeoff when setting the failure threshold in a circuit breaker?

Choosing how many failures trigger the circuit breaker is tricky. What is the main tradeoff?

A A low threshold may cause false alarms; a high threshold may delay failure detection.

B A low threshold causes data loss; a high threshold causes data duplication.

C A low threshold increases network traffic; a high threshold reduces security.

D A low threshold improves caching; a high threshold slows down encryption.

💡 Hint

Think about reacting too quickly versus too late.

If the failure threshold is too low, the circuit breaker may open unnecessarily (false alarms). If too high, it may keep calling a failing service too long, causing more problems.

❓ estimation

expert

Estimate the maximum number of failed requests allowed before the circuit breaker opens, given these parameters:

A circuit breaker is configured with a failure threshold of 5 failures within a 1-minute window. If the service receives 100 requests per minute and 4% of requests fail, how many failed requests will occur before the circuit breaker opens?

A 1 failed request

B 5 failed requests

C 4 failed requests

D 20 failed requests

💡 Hint

Calculate 4% of 100 requests, then compare to threshold.

4% of 100 requests = 4 failures per minute, which is below the threshold of 5. The circuit breaker opens only after 5 failures.