The difference between load testing and stress testing

October 10, 2014

The purpose of all testing in IT development is simply to see if the infrastructure works properly and consistently. For this reason, performance testing is one of the most important tests an IT department can run. The infrastructure on which the entire business is run cannot be interrupted without the company sustaining losses of both time and money.

Load testing, which could be seen more generally as performance testing, and stress testing are often done in conjunction with one another. While they certainly have some similarities, they both have separate functions in the overall testing process.

What is load testing?
TechTarget defines load testing as the process of subjecting a computer, network, or server to a normal or expected workload. Essentially, the tester wants to know how the system is going to function in the real world when it is faced with routine use. The test does this by including pauses between its requests, much like a human user would do.

Some examples of load testing include:

  • Downloading a heavy volume of files at once
  • Running multiple applications simultaneously
  • Seeing how a server reacts to a large amount of email at once

Load testing is generally conducted in two ways. One is called longevity testing, or testing how the system handles an expected workload over a long period of time. Another is volume testing, or finding out how the system can handle a spike in workload over a short period of time. 

What is stress testing
Stress testing is similar to load testing in that the kinds of tests that are run are essentially the same. What makes it different is that instead of subjecting a system to normal or expected usage, the tester puts the system under an extreme amount of strain, such as send a high volume of server requests with no pauses between, in order to see how the system performs under these unusual conditions. Techopedia noted that it's not enough to only run a regular load test

It's important to see how the system is going to handle the inevitable overload that can occur for any business' infrastructure. Additionally, stress testing gives the IT department a way to see how the system can react to partial outages, which is an integral part of planning for disaster recovery and business continuity.