Is Your Load Generator Launching Web Requests in Bunches?

TL;DR

This paper examines how load generators can produce more realistic web request patterns by avoiding synchronized request dispatches, which distort workload simulation and response time metrics.

Contribution

It introduces a method to identify and measure load generator request timing patterns, emphasizing the importance of mimicking real user request distributions.

Findings

Load generators often produce synchronized request bunches.

A tool is provided to measure and improve request timing realism.

Realistic request timing improves load test accuracy.

Abstract

One problem with load test quality, almost always overlooked, is the potential for the load generator's user thread pool to sync up and dispatch queries in bunches rather than independently from each other like real users initiate their requests. A spiky launch pattern misrepresents workload flow as well as yields erroneous application response time statistics. This paper describes what a real user request timing pattern looks like, illustrates how to identify it in the load generation environment, and exercises a free downloadable tool which measures how well the load generator is mimicking the timing pattern of real web user requests.