What Is Load Testing and How Does It Work?

What Is Load Testing and How Does It Work?

What is Load Testing

When anything is under construction, scrutiny takes place at different levels to be sure that the final piece is adequate in every way. It is the same thing with app developers when they are coding software. They perform various types of tests at different levels of development.

Without such tests, the shortcomings of the app wouldn’t be discovered and corrected and the app would fail when sent to the market. Load testing is one of the performance tests that are conducted when apps are built, but what is load testing, and what is its importance?

Load testing specifically targets the performance of the app after the expected large number of users start using it. Would the app be able to take it? Or would it fail miserably? These are what you find out from load testing.

Other tests are also conducted to help you evaluate the general app performance, identify bugs and loopholes so you can fix them. They are all performance testing and come in handy during application development.

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What Is Load Testing?

Load testing is one of the performance tests that are conducted when an app is built. It accesses the performance of an app when multiple users try to use it by mimicking this condition. It’s important during the development stages of a back end or front end system as it gives a clue about their performance under high traffic. Load testing provides information about the challenges that exist and allows for improvement.

To get the best out of load testing, you must have heavy and reliable traffic as you perform the test. Load testing is performed with load generators. They generate the traffic and load on the system so that its scalability and performance can be tested. The load generator forwards the requests to the system and gets the response.

The response time is measured and information is gathered from this data. The information is then used to evaluate the system’s performance generally, and its performance under load. By this, the necessary adjustments that are needed would be obvious and fixed.

Importance of Load Testing

Many businesses have gone digital and are taking advantage of the vast audience and customer base that’s available on the internet. Customers also appreciate the convenience of shopping online and getting all the information they need at the click of the mouse.

For this to be possible, both parties rely on applications and other systems. Since both businesses and customers largely rely on this to carry out many functions, they must perform optimally. One way to be sure that these systems can withstand the needs of the public is to carry out load testing on them.

Over the years due to technological advancements, the standard for apps and systems has risen, and it falls to the developers to meet this standard. If your software doesn’t meet up to the expectations, it can cost you some money.

Gartner states that the average loss during network downtime is $5,600 for every minute. Such production losses can be avoided with performance testing such as load testing.

To answer the question, “what is load testing?”, it can also be described as a test that truly proves that your application can perform satisfactorily under high traffic or load in production.  Systems that do well during routine tests don’t always do well under load and this test shows areas of weakness so that the glitch can be fixed before the system becomes available for use.

Performance testing generally is important as it helps you cut down on risk. The risk could be to your company, risk to your software, or risk to your customers. What affects one of these can affect all and so you need to have early foresight to prevent anything from going wrong.

How to Perform Load Testing

  1. First, have a dedicated environment that would be used for the test. This environment should be as close to the production environment as is possible.
  2. Next, define what the performance metrics for the test would be, and the criteria for success after the test.
  3. Have a detailed test plan that clearly defines all parameters. It should be detailed and thorough
  4. Have a baseline below which you know the test isn’t going well. This baseline would guide you when evaluating the result of the test.
  5. Run the test after the scheduling has been set and the scenario has been configured. By this time, traffic would be received as the system is in use by virtual users.
  6. After the test has been completed, the metrics would be collected, performance analyzed, and the shortcomings noted. Recommendations to fix whatever bottleneck that exists would then be provided and the issue fixed.
  7. After fixing the issues, the test would be performed again, and the results collected and analyzed.

Load Testing vs Stress Testing

Both load and stress testing are types of performance testing and are necessary when building a system. Load testing is done to check a system’s response and performance to the load it was built to bear.

Stress testing on the other hand is done to access a system’s response to overloading and very high traffic. It’s used on a system by placing it in an environment with unlikely scenarios.

With load testing, all we are interested in is that the system can do what it was made to do. But in load testing, we push the system beyond its limit. Both types of performance tests are used to determine how well front end systems or back end systems perform when they are being used by the intended users.

When you perform stress testing, you are deliberately breaking the system by exposing it to conditions that make it fail. After seeing the process, you can then tweak the program so that its break down at this point is more acceptable. It gives you data on how far a system can go under stress so you can establish its upper limit.

Load testing is done in normal conditions. It shows you an application’s response to user traffic under normal circumstances.

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Benefits of Load Testing

  • Load testing helps you reduce the expenses you would have to make due to failures in your system. After an app is launched and users begin using them, any failures at this point would be more expensive.
  • With load testing, the likely scenarios that make a system crash would be detected. It provides you with the problem before it arises so that you can get a solution before it becomes a problem.
  • The shortcomings of a system are discovered on time. Doing this prevents crashes during use thereby reducing the losses you would have faced.
  • Load testing lets you know the limit to which your system can perform. By this, you know the infrastructural needs of your system with growth to avoid a crash.
  • Load testing also helps you provide your customers with a consistently good experience and speed. The rise in traffic wouldn’t slow down the system as you would have equipped your app to handle the situation during load testing.

Best Load Testing Practices

  1. Have a clearly defined scope for the test you would be performing. This way, you will know what to expect and plan your guidelines appropriately.
  2. Take both positive and negative scenarios into account when designing the load test. Your app won’t always be in favorable situations and so you should consider these too during the test.
  3. The goal of this test is to provide better customer satisfaction. So always have this at the back of your mind and work towards achieving this.
  4. Have an environment that is similar to the production environment, and test your system on various grounds. These include security, networks, software, hardware, etc.
  5. The tools you use has a great influence on the result you get from the test. So choose a suitable tool for your task and goal.
  6. Focus on criteria and track it under load. This way, you get specific and focused results that are accurate.
  7. Have a set-out increment value while running the test. This way, you will know the volume of traffic that affects your system’s performance.

Real-Life Use Cases of Load Testing

  • Load testing can be used to evaluate the performance of a government website especially in times of expected high traffic. 
  • When large files are downloaded in huge numbers from a website.
  • An airline or online retail store can use load testing to evaluate their servers right before the launch of a promo that would attract over 10,000 users at a time.
  • Several commands can be sent to a printer at once to see how the queue affects the printer’s performance.
  • The continuous transfer of large files from a hard disc and to it.

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Guide for Choosing a Load Testing Tool

There are a lot of load testing tools out there, and finding the right one for your task is important. The following are factors to consider when choosing a load testing tool:

  • Choose a tool that allows you room for flexibility. Go for a tool that allows you to vary the test scenarios, the number of users, and use cases, etc.
  • A load testing tool that allows you easily create realistic load tests even the most complex ones would be more beneficial.
  • Go for load testing tools that allow for easy integration with other tools you use.
  • Does it provide you with accurate results?

Types of Load Testing Tools

Open Source Load Testing Tools

Open source load testing tools are free. They may however not be as sophisticated as the ones with licenses or internally developed.

Internally Developed Load Testing Tools

A company can choose to design its load testing tools to meet its needs specifically. This type of load testing tool however requires professional skills and a dedicated team to take charge of the building and maintenance.

Manual Load Testing Tools

Manual load testing can also be done manually. It is not as efficient as the automated ones due to the number of limitations it has. It is time-consuming and takes a lot of resources to perform.

Licensed Load Testing Tool

Licensed load testing tools can be used for different applications, are flexible, and can be used as many times as is required.


Load testing is an important part of every application development process, and it has numerous benefits. It helps the company detect weaknesses in its system before it causes any loss of revenue. It also helps with good user experience as you can put the infrastructure in place to cater to your audience.

Load testing is a continuous process and there are guidelines to ensure maximum benefit from it. So when the question “what is load testing” comes to your mind, note it as the performance of your system before it becomes publicly available.

About the author

Rachael Chapman

A Complete Gamer and a Tech Geek. Brings out all her thoughts and Love in Writing Techie Blogs.

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