Fault Tolerance in Distributed Systems

How to prevent communication outages in decentralized networks

Next Module: Consensus Algorithms

Why Fault Tolerance Matters

Fault tolerance is crucial in distributed systems where failures are inevitable. This module covers core principles and patterns to build resilient systems.

Key Concepts

  • Replication: Multiple instances of services
  • Redundancy: Backup systems for critical operations
  • Auto-Repair: Self-healing system components
  • Circuit Breakers: Prevent cascading failures

Common Architectures

Microservices Mesh

Multiple service instances communicating through service meshes like Istio or Linkerd

Distributed Task Queues

Queuing systems like Celery or Sidekiq to handle task retries and worker failures

Implementation Patterns

// Simple retry pattern example
function handleRequest(url, maxRetries = 3) {
  let attempts = 0;
  return new Promise((resolve, reject) => {
    function attempt() {
      fetch(url)
        .then(response => resolve(response))
        .catch(() => {
          if (attempts >= maxRetries) reject("Too many retries");
          attempts++;
          setTimeout(attempt, 1000 * Math.pow(2, attempts));
        });
    }
    attempt();
  });
}