Advanced System design concept · Real Systems & Production Thinking · 32 mins read
Fault Tolerance & Reliability
Design for failure so production issues degrade gracefully instead of cascading.
Retries
Try again carefully when a failure is transient, not permanent.
Intuition
Some failures are transient, so one more attempt can succeed. Retries exist to recover from brief overloads or network blips without manual intervention. Try again carefully when a failure is transient, not permanent.
Mental Model
Use capped exponential backoff, jitter, timeouts, and idempotent operations for external APIs, webhooks, or inter-service calls that often recover quickly.
Examples
- Use capped exponential backoff, jitter, timeouts, and idempotent operations for external APIs, webhooks, or inter-service calls that often recover quickly.
When to Avoid
Retries raise success rates, but they also add latency and can overload a struggling dependency. Blind immediate retries are one of the fastest ways to worsen an outage.
Circuit Breakers
Fail fast when a dependency is unhealthy instead of hammering it.
This section is part of the full PRISM roadmap, with worked examples, trade-off tables, interview questions and a quiz.
Unlock the full lessonPractice fault tolerance & reliability in PRISM
Concepts stick when you watch them fail. Build an architecture that depends on fault tolerance & reliability, push traffic through it in the PRISM simulator, and see the latency and error rates change as you adjust the design.