In the next chapter, we dive deep into performance metrics -- response time, throughput, error rate, latency, and resource utilization. You will learn exactly what numbers to look at, what they mean, and what thresholds to set. This is the foundation for everything you will do with JMeter and Gatling.
Q: What is performance testing and why is it important? Walk me through the different types.
A: Performance testing determines how a system behaves under load. It answers three questions functional testing cannot: how fast is it, how much can it handle, and how stable is it over time. There are five types: (1) Load testing verifies the system handles expected traffic -- 500 users for 30 minutes. (2) Stress testing finds the breaking point by gradually increasing beyond expected load. (3) Spike testing simulates sudden traffic bursts like flash sales. (4) Soak testing runs expected load for hours to find memory leaks and resource exhaustion. (5) Scalability testing measures whether adding resources improves performance proportionally. Every project needs at least load testing. The specific types needed depend on the risk profile -- e-commerce needs spike tests, 24/7 services need soak tests, growing startups need scalability tests.
Key Point: Performance testing is not optional. It is the difference between deploying with confidence and deploying with hope. Start with load testing, understand the five types, and test early and often.
Key Point: Performance testing proves your system works under real-world conditions -- start with load testing and expand based on risk
Answer all 5 questions, then submit to see your score.
1. What question does performance testing answer that functional testing cannot?
2. Which type of performance test is designed to find memory leaks?
3. What is the N+1 query problem?
4. Why should you use p95 instead of average response time for pass/fail criteria?
5. When should performance testing be done in the development lifecycle?