Load and performance testing

If you’re a developer, QA engineer or DevOps, you know you need to conduct different types of performance tests, to make sure each code change or feature added (a) doesn’t break the system, and (b) works.

But which types of performance tests should you conduct, what’s the difference between load tests and other types of tests and which test is suitable for which situation? In this blog post we’ll cover the answers to these questions, and more.

What is Performance Testing?

Performance testing is the general name for tests that check how the system behaves and performs. Performance testing examines responsiveness, stability, scalability, reliability, speed and resource usage of your software and infrastructure. Different types of performance tests provide you with different data, as we will further detail.

Before performance testing, it’s important to determine your system’s business goals, so you can tell if your system behaves satisfactorily or not according to your customers’ needs. 

After running performance tests, you can analyze different KPIs, such as the number of virtual users, hits per second, errors per second, response time, latency and bytes per second (throughput), as well as the correlations between them. Through the reports you can identify bottlenecks, bugs and errors, an decide what needs to be done.

When should you use Performance Testing?

When you want to check your website performance and app performance, as well as servers, databases, networks, etc. If you work with the waterfall methodology, then at least each time you release a version. If you’re shifting left and going agile, you should test continuously.

This is an example of a performance test report on CA BlazeMeter. This is a good test, as the growing number of users doesn’t affect the response time, the error rate continues to be low and the hits per second rises with the number of users but remains stable.

What is Load Testing?

Load testing is testing that checks how systems function under a heavy number of concurrent virtual users performing transactions over a certain period of time. Or in other words, how systems handle heavy load volumes. There are a few types of open-source load testing tools, with JMeter being the most popular one.

When should you use Load Testing?

When you want to determine how many users your system can handle. You can determine different user scenarios that let you focus on different parts of your system, like the checkout webpage on your website or app for web load testing. You can also determine how the load behaves, like the geo-location users come from or how the load builds and sustains in the system. Basically, load testing is something you should do all the time, to ensure your system is always on point. That’s why it should be integrated into your Continuous Integration cycles, with tools like Jenkins and Taurus.

This is what a load test would look like in JMeter. This test analyzes adding 100 users every 30 seconds until reaching 1,000 users. The entire stepping process takes 300 seconds. After reaching 1,000 threads all of them will continue running and hitting the server together for 5 minutes.