JMeter Testing: Everything You Need to Know

JMeter is one of the most popular open source performance/load testing tools. Used mainly for testing web applications, JMeter is Java-based and can be run from its GUI or in Command Line Mode (CLI).

JMeter testing is highly flexible and extensible for many use cases, thanks to a wide variety of testing plugins that expand JMeter’s core capabilities. JMeter’s plugins are developed by the open source community and available through the JMeter Plugins Manager, which is an independent open source project.

Consider this your starter guide to JMeter testing.

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Compare JMeter vs. Other Solutions

While JMeter testing is highly popular for load testing, it is not the only solution available for testers and developers. JMeter is not even the only open source testing solution. That is why it is important to compare JMeter to the other available testing solutions before choosing which one to use.

We recommend picking a testing solution based on your specific needs. Your considerations might include your tech stack, your testing use cases, the available skill set you have on your team, your CI/CD requirements (which you might have to check with DevOps), and more.

Let’s compare JMeter to some of the other testing solutions out there.

Selenium vs. JMeter

When comparing Selenium vs. JMeter you will see that they are both open source testing tools. However, each of them has different usages. While JMeter is mostly used for load testing (and its subtypes - stress testing, smoke testing, etc.), Selenium is recommended for functional and GUI testing for browsers. Together, they provide testers with a wide variety of testing capabilities.

JMeter vs. Locust

JMeter vs. Locust is a fairer comparison, since they are both open source load testing tools. The main difference between the two is that Locust is more powerful for writing tests as code (which are written in Python and not in Java), while JMeter has a more powerful GUI. In addition, JMeter provides more functionalities, while Locust requires less resources to run. 

JMeter vs. LoadRunner

When teams compare JMeter vs LoadRunner, they are often weighing the pros and cons of open-source to commercial solutions, respectively. LoadRunner is an expensive commercial tool, cumbersome to use, and cannot leverage the open source community for development. On the other hand, there is some variety in the capabilities between the two tools.

JMeter vs. BlazeMeter

Last but not least, JMeter scripts can be leveraged to run in BlazeMeter. In BlazeMeter, testers can achieve even more scalability, advanced reporting, more integrations and the ability to generate test data for their load tests.

Types of Testing With JMeter

JMeter is a flexible testing tool that supports different types of tests. While its forte is load testing, testers and developers can also use JMeter to run additional types of tests, if they need to. These include the following:

• Performance testing. Teams most often use JMeter for performance testing of web applications, web services, shell scripts, databases and more. Testing performance includes examining the load speed, system reliability and how the application handles a heavy load of users.
• Load testing. A subset of performance testing (or a term that is sometimes used interchangeably with “performance testing”), JMeter load testing examines how the application behaves under heavy loads to ensure it still performs as expected. Common techniques for load testing in JMeter include the Stepping and Concurrency Thread Groups.
• Stress testing. Another type of load testing that can be run in JMeter is stress testing. When doing stress testing, the load is ramped up to simulate extreme conditions, to examine system robustness. To run a stress test in JMeter, the test needs to be configured to ramp up to a high number of users, fairly quickly.
• API testing. API testing with JMeter is performed by checking the values the tested API returns.
• Security testing. Teams can also use JMeter for security testing or some types of vulnerability uncovering, such as site spidering, fuzzing, and DDOS.

Getting Started With JMeter Testing

So you’re convinced JMeter can help you with load testing applications. But now what? The first step is to install JMeter. You will need to install Java and then download JMeter from the official website.

Once you’ve installed JMeter, it’s recommended to get yourself accustomed to the tool by building a simple test script, which you can learn how to do from this JMeter tutorial. Get to know the GUI, components like Thread Groups, how to read the test results and how to resolve issues with JMeter scripts. Since the main question you’ll probably be using JMeter to answer concerns the number of concurrent users your application can handle, make sure your JMeter web testing represents real application usage.

If this is not your first load testing rodeo, you might need to perform a LoadRunner to JMeter script conversion. Additional advanced testing options include CI/CD integrations, for example a JMeter Jenkins integration or a CircleCI JMeter integration. By using these integrations you will be able to automate and schedule your load tests and improve your agility and code quality.

We’ve focused on the GUI option, but as you probably recall, JMeter also has a non-GUI mode, which you can leverage with the JMeter command line.

JMeter Testing Best Practices

Congratulations! You’re no longer a JMeter novice. Now, you’re probably looking for some JMeter testing best practices to help you optimize and improve your testing skills and abilities. We’ve compiled a few here:

• Learn how to update your JMeter ramp-up period based on your specific use case. JMeter provides multiple options for this.
• Learn to configure a test with a significant number of users. These could be thousands or millions. What’s important is that you learn how to test concurrent users using JMeter while you leverage your resources to do so, so you know how to reach the JMeter maximum concurrent users that you can.
• There are three main ways to perform JMeter parameterization: external files, databases and the Parameterized Controller plugin. Make sure you know when to choose and use each one.
• Don’t stick to the JMeter GUI components. Expand and extend their capabilities with code with JMeter Java classes, straight in GUI mode. Or, move straight to JMeter non-GUI mode.
• Most importantly, learn how to analyze test results with JMeter performance metrics to identify issues like bottlenecks and server health. You can use JMeter reporting or external tools like BlazeMeter, Grafana, or APMs.
• For ongoing support, tips, and collaboration with other testers, be sure to join the JMeter - Slack Community where users share insights, troubleshoot issues, and improve their JMeter skills together.

Making the Most of JMeter Plugins

JMeter is a powerful solution because of its core and its plugins. So far we’ve discussed its basic capabilities, but there are also 100+ plugins you can use to do more with your tests. These plugins’ abilities range from supporting more use cases to extending existing core capabilities to advanced reporting. While you will not need them all, there will be a dozen or so JMeter plugins that will probably come in handy for you.

JMeter plugins are accessed through a separate software, the JMeter Plugin Manager, that needs to be downloaded separately. If you’re keen on contributing to plugins, you can also introduce your own JMeter plugin development results, just like BlazeMeter often does, particularly with our JMeter correlation plugin.