circuit-breaker-pattern

name	circuit-breaker-pattern
description	Implement circuit breaker patterns for fault tolerance, automatic failure detection, and fallback mechanisms. Use when calling external services, handling cascading failures, or implementing resilience patterns.

Circuit Breaker Pattern

Table of Contents

• Overview
• When to Use
• Quick Start
• Reference Guides
• Best Practices

Overview

Implement circuit breaker patterns to prevent cascading failures and provide graceful degradation when dependencies fail.

When to Use

• External API calls
• Microservices communication
• Database connections
• Third-party service integrations
• Preventing cascading failures
• Implementing fallback mechanisms
• Rate limiting protection
• Timeout handling

Quick Start

Minimal working example:

enum CircuitState {
  CLOSED = "CLOSED",
  OPEN = "OPEN",
  HALF_OPEN = "HALF_OPEN",
}

interface CircuitBreakerConfig {
  failureThreshold: number;
  successThreshold: number;
  timeout: number;
  resetTimeout: number;
}

interface CircuitBreakerStats {
  failures: number;
  successes: number;
  consecutiveFailures: number;
  consecutiveSuccesses: number;
  lastFailureTime?: number;
}

class CircuitBreaker {
  private state: CircuitState = CircuitState.CLOSED;
  private stats: CircuitBreakerStats = {
    failures: 0,
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide	Contents
TypeScript Circuit Breaker	TypeScript Circuit Breaker
Circuit Breaker with Monitoring	Circuit Breaker with Monitoring
Opossum-Style Circuit Breaker (Node.js)	Opossum-Style Circuit Breaker (Node.js)
Python Circuit Breaker	Python Circuit Breaker
Resilience4j-Style (Java)	Resilience4j-Style (Java)

Best Practices

✅ DO

• Use appropriate thresholds for your use case
• Implement fallback mechanisms
• Monitor circuit breaker states
• Set reasonable timeouts
• Use exponential backoff
• Log state transitions
• Alert on frequent trips
• Test circuit breaker behavior
• Use per-dependency breakers
• Implement health checks

❌ DON'T

• Use same breaker for all dependencies
• Set unrealistic thresholds
• Skip fallback implementation
• Ignore open circuit breakers
• Use overly aggressive reset timeouts
• Forget to monitor