27 July 2018

What Is Load Testing?


Any software developer worth their salt knows that performance tests are part and parcel of creating a well-functioning program. These vital trials are designed to ascertain a software’s stability, responsiveness, scalability, and other critical factors, but not every performance test is designed with the same goals in mind.

Spike testing, for instance, measures how well systems can perform when exposed to sudden “spikes” in user load, while endurance tests are done to ensure that software can handle user loads for an extended period of time.

There are a wide variety of performance tests, but today, we’re going to focus on one in particular: load testing. This particular performance test is all about judging performance under anticipated heavy user loads, and we’re going to explain how it’s done and what makes it so crucial.

Load Testing Explained

In brief, load testing is an attempt to determine a system’s ability to handle multiple numbers of simultaneous users over a period of time. In other words, how it might perform in conditions that are close to what would be considered “real life.”

It’s similar to, but distinct from stress testing, in which the breaking point of a system is being tested.

Load testing is commonly performed on web-based applications, and used to get a sense of how many users a system can support, if current infrastructure is sufficient, and how sustainable software might be at peak user loads.

Load testing is useful for identifying performance bottlenecks before a product goes to production and mitigating the risk of downtime, which, in turn, reduces the potential of system failures and increases overall customer satisfaction.

Consider a scenario in which users of a system cannot access it because of increased traffic. The resulting downtime or even just minor delays in service, can be deleterious to business, as the organization in question loses out on revenue from potential users and must burn funds in getting their system back in well-functioning order.

Hence, thorough load testing can help optimize system performance by identifying potential weaknesses in handling a large volume of users, creating a greater level of confidence in both reliability and performance.

How Load Tests Are Performed

Developers undertaking load tests will look at specific factors to determine a system’s performance abilities. These include metrics like transaction response times and network delays between client and server. They also delve into server/hardware limitation issues, software design issues, and gauge how well their system performs under various simulated loads.

This can be approached in several ways. Developers could, for instance, attempt to perform manual tests, but this often results in a difficult to coordinate, nearly-impossible to measure, and often -unrepeatable results. For more precise and repeatable results, developers will more often than not use specialized testing tools.

Such options can be thought of as analytical software that will generate simulated user loads against which a system can be tested, then aid developers in measuring and making sense of the results. Testing tools might be created in-house, developed by a third party, or procured from some open-source solution.

Whereas third-party, enterprise solutions will often offer robust protocols and help simulate massive user loads, their open-source (and generally less expensive) counterparts are typically not so full-featured. In-house testing solutions can be tailored for specific need, but also require an investment of time to build.

It’s up to development teams to ascertain which option works best for their particular situation, but once a testing solution is secured, the procedure for load testing is, by-and-large, the same across the board. Using a dedicated testing environment, developers will run and monitor various scenarios, then analyze the results.

These results will become the basis for recommendations on fine-tuning the software to perform better, handle more users, etc. Whatever specific business goals they might have in mind before running their tests, that’s what developers will work toward, and executing this particularperformance testis one of many steps along the path to success.


Load testing is vital for ensuring an application can handle sizable user loads. This goes a long way in making certain software is scalable, reliable, and won’t fail when multiple customers are making use of it. To learn more, be sure to check out additional resources, for instance –what is load testing by Stackify, and keep this critical performance monitor in mind when trying to make sure your products are working their best.

Jakub Dobrowolski
Software Quality Assurance Engineer