Why Load Test#

Performance problems discovered in production are expensive. A service that handles 100 requests per second in dev might collapse at 500 in production because connection pools exhaust, garbage collection pauses compound, or a downstream service starts throttling. Load testing reveals these limits before users do.

Load testing answers specific questions: What is the maximum throughput before errors start? At what concurrency does latency degrade beyond acceptable limits? Can the system sustain expected traffic for hours without resource leaks? Will a traffic spike cause cascading failures?

Scenario: Preparing for and Handling a Traffic Spike#

You are helping when someone says: “we have a big launch next week,” “Black Friday is coming,” or “traffic is suddenly 3x normal and climbing.” These are two distinct problems – proactive preparation for a known event and reactive response to an unexpected surge – but they share the same infrastructure mechanics.

The key principle: Kubernetes autoscaling has latency. HPA takes 15-30 seconds to detect increased load and scale pods. Cluster Autoscaler takes 3-7 minutes to provision new nodes. If your traffic spike is faster than your scaling speed, users hit errors during the gap. Proactive preparation eliminates this gap. Reactive response minimizes it.