The Ultimate JMeter Tutorial for Beginners for Performance Testing

The demand for JMeter experts who can evaluate the scalability and performance of applications in these intricate environments is also growing as cloud computing and microservices architectures gain popularity. Gaining proficiency with JMeter can lead to a variety of job options in the quality assurance and software testing fields. This JMeter Tutorial for beginners will help you get started. Explore our JMeter course syllabus.

JMeter Basics for Beginners

JMeter is a reliable tool for determining how well your application, website, or API performs under various stress conditions. Below is a summary of the core JMeter concepts:

What is Performance Testing?

It’s helpful to understand why we use JMeter before delving into it. Assessing a system’s speed, responsiveness, reliability, and scalability is the main goal of performance testing. It provides solutions for the following questions:

• How many people can our website support at once without experiencing a crash?
• How fast does a specific page load when there is a lot of traffic?
• When numerous queries are received at once, can our API continue to function as intended?
• Is the system able to sustain a high load for an extended period of time?

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Introducing Apache JMeter:

JMeter is a robust, open-source Java program made for performance evaluation and functional behavior load testing. It was initially created to test Web applications, but it has now been extended to test other resources as well. Important information to be aware of:

• Open Source: You can use and alter it for free.
• Java-Based: Necessitates the installation of Java on your computer.
• GUI (Graphical User Interface): It offers an easy-to-use interface for maintaining and developing test plans.
• CLI (Command-Line Interface): Tests can be done non-interactively using this, which is essential for automation and load creation from various machines.
• Extensible: Allows for plugins to increase its capability for a range of reporting and protocols.

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Core Concepts in JMeter

The building blocks of JMeter are as follows:

Test Plan:

The top-level container for all of your test components is called the test plan. It basically lays up your whole test scenario. Consider it your performance test’s template.

Thread Group: 

This mimics several virtual users simultaneously accessing your program. You specify:

• Number of Threads (Users): The quantity of simulated users that should be executed.
• Ramp-Up Period: The amount of time it takes for each thread to begin running. For instance, each thread will begin 0.5 seconds after the one before it if you have 10 threads and a ramp-up of 5 seconds.
• Loop Count: The number of times the test steps should be run by each thread.

Samplers: 

These inform JMeter of the type of queries that should be sent to the intended application. Typical samplers consist of:

• HTTP Request: To test web servers (websites, web apps), send an HTTP request. The URL, parameters, headers, HTTP method (GET, POST, PUT, DELETE), etc. are all specified by you.
• JDBC Request: To evaluate the performance of the database.
• FTP Request: To evaluate the performance of the FTP server.
• SOAP/XML-RPC Request: For XML-RPC or SOAP web service testing.
• JMS Publisher/Subscriber: For testing messaging systems, use this.

Listeners: 

These show your test results in a variety of formats. Among the crucial listeners are:

• View Results Tree: Provides debugging information for each request and response.
• Summary Report: A statistical summary of the test findings, including the number of samples, average reaction time, error rate, and throughput, is provided in this.
• Aggregate Report: Similar to the Summary Report, the Aggregate Report combines data from several samplers under the same name.
• Graph Results: Shows response times as a function of time.
• Table: Presents the findings in tabular form.

Configuration Elements: 

You may set up and customize your test environment with the use of configuration elements. Among the examples are:

• HTTP Request Defaults: You can specify default parameters (such as the IP address or server name) for your HTTP queries using it, which removes the need to repeat them in each sampling.
• HTTP Header Manager: Custom HTTP headers, such as user-agent and content-type, can be added to your requests using it.
• HTTP Cookie Manager: Manages cookies for your web application testing automatically.
• CSV Data Set Config: This feature lets you read test data from a CSV file, such as passwords and usernames.

Pre-Processors: 

These run ahead of a sampler. They are frequently employed to change request parameters or retrieve information from earlier answers. Among the examples are:

• User Parameters: Give each virtual user its own set of settings.
• Regular Expression Extractor: Uses regular expressions to retrieve data from a server response.

Post-Processors: 

They run after the sampler. Usually, they are employed to retrieve information from the answer for use in later queries. Another popular post-processor is the Regular Expression Extractor.

Assertions: 

You can confirm that the server’s answer satisfies your requirements by using assertions. Response code, response content, response headers, and other elements are all subject to assertion. Typical claims consist of:

• Response Assertion: Verifies whether a regular expression or specific text is present in the answer.
• Duration Assertion: Verifies that the response time falls within a predetermined range using the duration assertion.
• Size Assertion: Verifies the response’s dimensions.

Controllers: 

These govern how your test strategy proceeds. Among the examples are:

• Simple Controller: Organizes samplers by grouping them together.
• Loop Controller: Performs a certain amount of executions of its child elements.
• If Controller: Based on a condition, it executes its child elements.
• Transaction Controller: Calculates the overall execution time of a collection of samplers.

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JMeter Automation Step by Step

Here is the basic workflow of JMeter automation. JMeter testing process involves the following steps:

Step 1: Create a Test Plan

Specify the general objectives and parameters of your test.

• Open JMeter: Open the JMeter software. A blank test plan will be your starting point.
• Rename the Test Plan (Optional but Recommended): In the left-hand tree, right-click on the “Test Plan” node. Choose “Rename” and label it with a meaningful term, such as “Homepage Performance Test”.

Step 2: Add a Thread Group

Set up how many virtual users there are and how they behave.

The Thread Group will simulate our 5 users.

• Select the “Test Plan” node with a right-click.
• Select Add > Threads (Users) > Thread Group.
• Set up the following in the “Thread Group” control panel:
  • Name: Give it a name that makes sense, such as “Homepage Users”.
  • Number of Threads (users): Enter 5. This will simulate 5 users using the system at once.
  • Ramp-up Period (in seconds): For the period (in seconds), the ramp-up Enter 1. Consequently, in less than a second, JMeter will gradually activate each of the five users.
  • Loop Count: Enter 2. The homepage will be accessed twice by each of the five users.

Step 3: Add Samplers

Define the precise requests you wish to send to your application by adding samplers.

JMeter will be instructed to send a request to the website’s homepage using the HTTP Request sampler.

• The “Homepage Users” Thread Group can be right-clicked.
• Select Add > Sampler > HTTP Request.
• Set up the following in the “HTTP Request” control panel:
• Name: Give it a name that describes it, such as “Homepage Request”.
• Web Server: 
  • Protocol [http]: If the website utilizes HTTPS, leave it at http (or https).
  • Server Name or IP: Enter example.com.
• HTTP Request:
  • Method: Since we are only requesting the homepage, choose GET.
  • Path: Type /, which is the homepage’s root path.

Step 4: Add Listeners

Select how you wish to see and interpret the test findings.

If you want to see how your test went, you need listeners. Let’s include some typical ones.

• The “Homepage Users” Thread Group can be right-clicked.
• Select Add > Listener > View Results Tree. This displays details about every request and answer.
• The “Homepage Users” Thread Group can be right-clicked.
• Select Add > Listener > Summary Report. This gives a summary of the test’s statistics.
• The “Homepage Users” Thread Group can be right-clicked.
• Select Add > Listener > Graph Results. The response times are visualized in this way.

Add Configuration Elements (Optional) 

Control headers and cookies, establish default settings, etc.

Add Pre- and Post-Processors (Optional): 

Change requests or take information.

Add Assertions (Optional): 

Confirm that the answers are accurate.

Step 5: Run the Test

Carry out your test strategy. It’s time to carry out your test strategy.

• Save your Test Plan: Go to File > Save As – Save your test plan with a.jmx extension (homepage_test.jmx)
• Run the Test: Either choose Run > Start or click the green “Play” icon in the toolbar.

Step 6: Analyze the Results

Analyze the listeners to determine how well your application is performing.

The listeners will begin displaying data while the test is running:

View Results Tree: Each of the five users who accessed the webpage twice will have its own entry, for a total of ten entries. 

• To view information about the request sent, the server’s response (including HTML content), the response headers, and the time spent, click on each entry. 
• Check for any mistakes, which are indicated in red.

Summary Report: This listener will display statistics such as these after the test is finished.

• Label: The sampler’s name (“Homepage Request”) is the label.
• Samples: The total number of requests, which in our situation should be 10.
• Average: The mean millisecond response time.
• Min: The bare minimum of reaction time.
• Max: The fastest possible reaction time.
• Error %: The proportion of unsuccessful requests, ideally at zero.
• Throughput: How many requests are handled in a second.
• Sent/Received: The volume of data sent and received.

Graph Results: A graph illustrating each request’s response time over time will be displayed. A visual representation of the performance is available.

Step 7: Interpret and Iterate (if needed)

Tune and Rerun (if necessary): Adapt your application or test strategy in light of the results.

Example.com’s performance under this light load can be evaluated based on the listeners’ results. You may need to conduct additional research or modify your test strategy for a more thorough analysis if you noticed mistakes or extremely long response times.

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Conclusion

This JMeter beginner tutorial covers the basic concepts and detailed workflow. With our JMeter testing courses in Chennai, you may practice performance testing using the JMeter testing tool.