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A Developer’s Guide to Continuous Performance Testing

One of the most important phrases of DevOps practices is “Test early, test often.” It’s crucial to perform functional testing early with unit tests and integration tests. But it’s equally important to perform non-functional testing. That means you should have performance tests. As markets become more saturated with each passing day, you no longer have the luxury to postpone performance testing until all features are developed. Continuous performance testing has been gaining popularity as more teams realize the importance of continuous testing. Continuous performance testing is done on every code commit, and it eliminates the need for manual performance tests that can be time-consuming and expensive.

This article will share how continuous performance testing works, why it’s essential, and what tools you’ll need to get started with continuous performance testing on your team.

Why Do You Need Continuous Performance Testing?

Continuous performance testing is the continuous monitoring of the performance of an application under increased load. Teams can monitor and test performance manually in a testing environment, but this only works on small systems and on a limited scale.

You often see performance testing on major releases, but few teams do it as part of their DevOps process in the CI/CD pipeline.

DevOps process. Image from Pixabay

Continuous performance testing during the project’s development phase is recommended, but it requires a whole new set of tools to run and scale automatically. However, there are several use cases where continuous performance testing is essential nonetheless:

  • It prevents major outages
  • It improves customer experience
  • It ensures performance service-level agreements (SLA) are met
  • It ensures that performance doesn’t slip over time
  • It helps in finding and resolving application performance problems faster

What Is Continuous Performance Testing?

Performance testing is a type of testing that focuses on the performance of the application. There are a lot of types of performance testing, but the one that is used often in continuous testing is load testing. Load tests are designed to simulate the activity of multiple users accessing software simultaneously.

The goal is to test the limits of how many requests the application can process without jeopardizing the system’s stability. Load tests are often automated with scripting languages for better execution control and accuracy.

When you mention performance testing, most developers think that about these steps that you take in the later stages of the application development:

  1. First, you identify all the important features that you want to test.
  2. Then you spend weeks working on test scripts that will perform performance testing.
  3. Finally, you perform the testing and analyze the many pages of performance test results after that.

The above premise of performance testing was correct in the past, when most applications were developed using the waterfall approach.

However, the times have changed. The waterfall approach is now mostly a thing of the past. Software development has changed to be more agile, and as more and more teams use DevOps practices to develop and deploy their applications, the need for testing has changed—testing is now a part of the development process.

Getting early feedback from automated functional tests is crucial in increasing the quality of the code changes. These days, teams usually use automated tests to check that the application satisfies the functional requirements. But, it’s also vital to check the non-functional requirements—system indicators such as security, scalability, and performance. Performance requirements are especially important.

According to the Akamai Performance report, forty-nine percent of customers expect that a page will be fully loaded in two seconds. Eighteen percent of customers expect instant page load. Having to wait more than two to three seconds for a page to load is a thing of the past. Poor performance means the loss of a customer and valuable revenue. The unsatisfied potential buyer will leave and never come back.

Loyal customers are the lifeblood of every business. With their help, a company can grow its customer base, increase sales, and make more money. That is why continuous performance testing is a vital part of the software development process.

How Does It Differ From Regular Performance Testing?

Regular performance tests might be done on a release or at milestones rather than as part of CI. However, continuous performance testing can be done often and as part of every build.

Regular load testing focuses on how a specific version of the software performs in peak load situations. Continuous load testing ensures that every new version of the application will perform well when in peak load.

If a new version of the application doesn’t meet the necessary performance criteria, the whole build fails. After that, you need to go to the latest code changes and check and fix the performance issues. That means you can use continuous performance testing to validate code in continuous deployment pipelines, ensuring that there are no regressions in the performance of applications. Again, the goal is not just finding problems early, but being able to fix them quickly before they affect customers or users negatively.

While some companies find that continuous load testing is a great idea, some factors make using this method difficult, such as a shortage of production-like environments for different API versions and the lack of data around permutations of traffic.

How to Start With Continuous Performance Testing?

If you don’t do performance testing, your first encounter with sluggish applications and time-out issues will be from consumers who are unhappy with your product.

You need to measure your application’s performance now, not after the major outage. With continuous testing, you continuously keep an eye on how well your application responds to load. As a result, you can catch performance-related problems early and fix them before they become significant issues.

To start continuous performance testing, make sure that you have a continuous integration (CI) pipeline in place. The first step is to collect information from the business side. You need to consider what amount of requests you need to be able to handle to maintain the current business SLAs. Also, you need to think about critical features of your application: is that the login, order processing, or checkout functionality?

Next, you need to start with writing performance tests. Usually, the most straightforward approach to take is to start with testing the API layer.

You can do this using tools such as BlazeMeter, ReadyAPI from SmartBear, Speedscale, or Apache JMeter. There are plenty of tutorials on installing these tools, so this should not be overly complicated. Also, remember to store the tests under your main repository and treat them as first-class citizens. That means that you should pay attention to their quality.

The next step would be to choose the scenarios or use cases you want to test for continuous performance testing. Here are some tips on how to write the best scenarios:

  • Cover the most critical areas of the system first
  • Base your test scenarios on the most realistic user usage
  • Test for the end-to-end user experience
  • Use concrete numbers instead of vague terms like “a heavy load”

Finally, make sure to collect all your test results into reports that will be easy to read and understand. It’s vital to have meaningful reports so that you can plan your next steps well.

The cycle of continuous performance testing doesn’t end once you collect the results. You need to add all the performance issues to your product backlog and plan to fix them accordingly. The results of the initial performance test represent the baseline for all future tests.

Ideally, you would perform the above process in a test environment that closely mimics the production environment. However, a lot of companies test in production due to the following reasons:

  • It takes a lot of time to build test automation
  • It is hard to collect, understand, and replicate accurate data
  • It is expensive to maintain the production-like test environments

Benefits of Continuous Performance Testing

There are several benefits of continuous performance testing:

  • It ensures that your application is ready for production
  • It allows you to identify performance bottlenecks
  • It helps to detect bugs
  • It helps to detect performance regressions
  • It allows you to compare the performance of different releases

Performance testing should be continuous so that an issue does not go unnoticed for too long and hurt the user experience. Continuously testing will show you what your server load looks like at any given time, thereby giving insights into servers’ capacity limits and bottlenecks.

Drawbacks of Continuous Performance Testing

However, there are also some limitations to the continuous performance testing:

  • It’s not always easy to automate
  • It can be difficult to find test cases
  • You can’t load test everything
  • You need to keep your tests up-to-date
  • It isn’t always possible to test on live systems

You can mitigate many of these drawbacks if you perform continuous load testing correctly. Performance testing should be a continuous process—that means you add new test cases and update old ones as the application evolves so that your performance testing suite captures all relevant scenarios.

Who Is Most Likely to Get Value From Continuous Performance Testing?

This depends upon the company’s needs, but generally speaking, some companies will find continuous performance testing more valuable than others. These companies typically fall into the following areas:

  1. Companies that have a large user base.
  2. Companies that have a large volume of interaction regularly.
  3. Companies that have invested a lot of time or money into a project that has a long lifespan.
  4. Companies that have a large amount of staff available to them.

Each of these companies will be different in terms of what they need from a continuous performance testing system.

Teams that work on small applications and don’t expect high spikes in load don’t need to invest in continuous performance testing.

For example, if the application is a browser game where user actions are reasonably predictable and external inputs are moderate, there’s probably no reason to introduce continuous performance testing. Continuous performance testing for this type of application would likely reduce overall productivity more than improve anything. Instead, teams with these characteristics can focus more on doing periodic end-to-end tests, which gives them enough data to make meaningful decisions about architecture, trade-offs between the size of the application, and heavy workloads.

Conclusion

If you want to stay ahead of performance issues and outsmart your competition, continuous performance testing is the way forward.

The key takeaway here is that including performance monitoring in your development phase for new features or products before they go live will save time later during maintenance cycles when bugs are found. Development teams should always be looking for ways to improve their processes. With continuous performance testing, you won’t disrupt customers’ experience with future releases. This includes thinking about how much load each feature needs after being released into production.

Finally, when you continuously test your infrastructure, you ensure that its performance does not degrade over time. Your team should have a goal and track their results with metrics to ensure that you are making progress.

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