Advantages and Disadvantages of Load Testing: The Comprehensive Comparison

Downtime has proved to be one of the major reasons why businesses lose clients, their reputation, and money. In 2017, Information Technology Intelligence Consulting conducted research among more than 750 organizations to find out the average cost of a server outage. The findings suggest that almost a quarter of the reported server outages cost between $301K and $400K per hour. But the real losses may even go beyond these figures as they include the clients who’ll never go back and the purchases they’ll never make.

One of the reasons why servers go down and disrupt the normal operation of a business is their inability to handle massive traffic increases. To identify the maximum amount of load that the server can cope with and still function properly, load testing is performed.

In this article, we will describe what load testing is, its types, and also we will look at load testing from both sides.

What is load testing?

Let’s start with the definition of load testing itself. Load testing is a non-functional testing option that is responsible for creating real testing environments. With its help, testing engineers can see if the application functions properly within the limits of the expected load.

To put it simpler, load testing helps you understand if your app or website is going to survive when real people start using it. Load testing can find page load bugs, lags, and freezes that can appear during usage. It determines if the infrastructure is built correctly and if the current amount of resources is able to handle the highest expected load.

This task cannot be solved by single use cases, so load testing is what the app needs.

Why is load testing important?

Primarily, load testing aims to define how much load an application can handle without crashing or slowing down. The app may work fine during functional testing with even 100 QA engineers using it simultaneously. However, it can entirely or partially crash right after release when thousands of people start using it at the same time. That’s why load testing is required: It imitates the production environment to see if the product is able to handle real-life situations.

Other common reasons to introduce load testing into the development process include:

• Finding out if the app lives up to the required performance rates;
• Identifying bottlenecks that may later disrupt the app's performance;
• Ensuring safety of user data during peak traffic, etc.

Let’s imagine the situation. Today is Friday and you want to watch a new episode of your favorite TV show on a streaming service. You excitingly turn on the laptop, open the browser, click on the platform’s icon, but the service says “Sorry, the website is temporarily unavailable. Try again later.” There are high chances that you will get frustrated, especially if you get the same answer after several reloadings.

Load testing is needed for such a situation to never happen.

Performance testing vs load testing vs stress testing

Load testing is not the only option for checking the way the app is functioning and they can be easily confused with one another. A lot of people ask what is the difference between load testing, stress testing, and performance testing, and here is the answer.

• As we already said, load testing focuses on the maximum number of users an app can survive through without errors and downtimes.
• Stress testing checks whether an application can handle sharp increases in load intensity and work beyond its normal operational capacity. For example, stress testing is particularly useful for online shops or ticket booking sites that experience traffic surges during Black Friday or other sales events.
• Performance testing is the general name of the group of testing methods that are used for checking the system’s behavior, scalability, speed, and resource usage.

What are the advantages and disadvantages of load testing?

Since nothing is perfect in this world, load testing has two sides. There are several benefits that you will get if you use load testing:

• With its help, the identification of performance issues before release becomes a breeze.
• Load testing assists in building a scalable infrastructure.
• The chances of downtime are reduced to minimal.
• It improves the level of security.

Still, load testing has some drawbacks that you have to consider:

• Load testing tools require certain tech knowledge.
• A lot of load testing tools have licenses and charge fees for use.
• If set up incorrectly, load tests can lead to false performance issues and take more resources.

Now, when we highlighted the pros and cons of load testing, let’s talk about analyzing its results in more detail.

How to analyze load test results?

The results of load testing can seem tedious to review. Visualizing made it a lot easier, but you still have to know what to look at and what it all means. The metrics we are going to mention are the most important ones regarding the load tests.

Page load time

This characteristic shows how fast the pages of your app are displayed to users. You should definitely know these numbers. If they are too big, users will leave your app since they don’t like to wait. You can set up a Service Level Agreement (SLA) with the exact numbers or just monitor them regularly and keep them low.

Response load time

Page load time is not the only metric to look at. When a page is open but the content on it is not responsive enough, it still can affect the user experience. Load tests will help you define how much time users spent on the app’s pages and optimize the bottlenecks.

Errors and warning

This section will describe what errors can occur in the natural environment. It’s a crucial piece of knowledge since it allows you to quickly identify and fix possible errors. For example, server error 500s like 502 Bad Gateway, 503 Service Unavailable, or 504 Gateway Timeout are some of the most common errors that should be eliminated.

But what can happen if you ignore these results or don’t implement load testing at all?

What happens when you don't perform load testing?

You lose clients. When the app slows down and becomes inefficient, customer loyalty suffers first. Clients will hardly wait until the product is back on track again—they’ll simply switch to the competitors.

You lose money. Fixing the problem itself will give you a lot of unplanned expenses. Also add here the money you’ll never earn due to lost clients.

You lose your reputation. Failures and downtimes can contribute to the impression that the product is not reliable. Apps that work with sensitive data are likely to suffer really dreadful after-effects in this case, so banking and medical products are at the biggest risk.

When to start?

Typically, load tests start after functional tests are over and all bugs are fixed, which means the code works properly. Before embarking on load testing, it’s a good idea to define performance and stability requirements first. They may include the maximum response time, the number of requests the app should be able to process under the expected load, or other relevant metrics.

Load testing is a great tool to put your product in a real-life situation in order to identify its performance limits and see if these limits can be pushed further away. If you’re looking for a way to find out if your app lives up to the performance rates you’ve set and is able to withstand all the coming peak load situations, load testing is the right choice to help you along the way.

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