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Table of contents
1.
Introduction
2.
Most Asked JMeter Interview Questions and Answers
2.1.
1. What Is Jmeter, and How Does It Work?
2.2.
2. Describe Jmeter's architecture.
2.3.
3. What is a Thread Group in JMeter?
2.4.
4. What is Performance Testing, and why is it important?
2.5.
5. What is the definition of performance testing?
2.6.
6. What are the advantages of using the JMeter tool for performance testing?
2.7.
7. Is the JMeter tool capable of simulating a real browser?
2.8.
8. What is a Controller in JMeter?
2.9.
9. What are some of JMeter's characteristics?
2.10.
10. Describe how JMeter works internally.
2.11.
11. Do we need to know how to code to construct JMeter scripts?
2.12.
12. In JMeter, how are queries sent to the server?
2.13.
13. What understanding do you have of the correlation?
2.14.
14. What is the meaning of the Loop Count in a Jmeter?
2.15.
15. What is the Parameterization Process?
2.16.
16. What is the difference between Samplers and Thread Groups?
2.17.
17. In JMeter, what is the difference between a pre-and post-processor?
2.18.
18. What are Pre-processor Elements, and what do they do? What are some of the elements of the pre-processor?
2.19.
19. How does the Duration Assertion function within a Thread Group?
2.20.
20. What is a JMeter timer, and what are the different types?
2.21.
21. What should be the maximum number of threads on a single system?
2.22.
22. Explain how to use JMeter to perform spike testing.
2.23.
23. Is it required to explicitly call embedded resources in JMeter?
2.24.
24. Explain how you can use JMeter to capture the authentication window's script.
2.25.
25. What is the purpose of the Timer in JMeter?
2.26.
26. What are the advantages of using JMeter for performance testing?
2.27.
27. What is the definition of a workbench?
2.28.
28. In JMeter, what is a Gaussian timer?
2.29.
29. Discuss Poisson Random Timer.
2.30.
30. In JMeter, what are the various thread groups?
2.31.
31. How do you deal with sessions and cookies in JMeter?
2.32.
32. Why is running JMeter in GUI mode recommended?
2.33.
33. Is JMeter capable of running Selenium scripts? If so, how should you go about doing it?
2.34.
34. What is BeanShell scripting, and how does it work?
2.35.
35. What is the meaning of a Root CA certificate?
2.36.
36. What is Tidy Parsing, and how does it work?
2.37.
37. How would you handle dynamic parameters in JMeter scripts to ensure accurate load testing results?
2.38.
38. What is the purpose of the Ramp-Up Period in a Thread Group?
2.39.
39. How can you adjust the thread count within a Thread Group configuration?
2.40.
40. What are JMeter listeners and how can they be used to analyze and interpret test results effectively?
2.41.
41. How would you handle performance bottlenecks in JMeter tests and what techniques or strategies would you employ to optimize test scripts and improve performance?
3.
Tips
4.
Frequently Asked Questions
4.1.
What is JMeter mainly used for?
4.2.
Is JMeter easy or tough?
4.3.
What type of file is a JMeter script?
4.4.
What are the advantages of JMeter?
4.5.
Which testing is not supported by JMeter?
4.6.
Who mainly uses JMeter?
4.7.
In Selenium, what is JMeter?
4.8.
Is functional testing performed with JMeter?
5.
Conclusion
Last Updated: Mar 27, 2024
Medium

Top JMeter Interview Questions (2023)

Author Palak Mishra
0 upvote

Introduction

JMeter is a load-testing performance analysis and measuring tool. Our thorough list of JMeter interview questions will help you prepare for your interview. 

JMeter Interview Questions

You've come to the correct location if you need a reference guide before your Jmeter interview. Over 32 JMeter Interview questions are included in the blog.


Also Read: Java OOPs Interview Questions

Most Asked JMeter Interview Questions and Answers

1. What Is Jmeter, and How Does It Work?

Ans: JMeter is a Java tool for load testing client/server applications. Apache JMeter is open-source software that is a 100 percent Java desktop application used to load functional test functionality and assess application performance. Initially designed to test web applications, it has since been enhanced to cover more testing capabilities. 

2. Describe Jmeter's architecture.

Ans: Jmeter is a Java-based open-source tool created for load testing.

Jmeter supports all key protocols provided by Load Runner. Jmeter works on separate layers of protocols and does not execute JavaScript in HTML web pages, unlike any different browser.

3. What is a Thread Group in JMeter?

Ans: In JMeter, a Thread Group is a fundamental element that defines the execution characteristics of a test plan. It simulates the behavior of virtual users (threads) that will interact with your application. Thread Groups allow you to control how many users will access your application, how they will behave, and for how long.

4. What is Performance Testing, and why is it important?

Ans: Performance testing is non-functional testing that evaluates the application's performance under expected or higher loads. It's done before the app goes live to ensure it doesn't crash and replies in a reasonable amount of time under real-world conditions.

5. What is the definition of performance testing?

Ans: This test determines the best possible performance under a given infrastructure setup. It also shows any modifications that need to be made before the application goes live early in the testing process.

6. What are the advantages of using the JMeter tool for performance testing?

Ans: The following are some of the benefits of utilizing the JMeter tool for performance testing:

  • It is entirely free to use and has no licensing fees.
  • It's free and open-source. Put another way, anyone can tailor it to their specific needs.
  • JMeter has a robust online community as well as tutorials.
  • It can be used to test the performance of a wide range of applications. Websites, online services to FTP, and databases are just a few examples.
  • It's simple to understand and use.

7. Is the JMeter tool capable of simulating a real browser?

Ans: No, JMeter does not replicate or operate the same way as a genuine browser. It cannot render HTML responses as a real browser can.

8. What is a Controller in JMeter?

Ans: In JMeter, a Controller is a fundamental element used to organize and structure the execution of test plans. Controllers are responsible for defining the flow and logic of how samplers (requests or actions) are executed within a test script. They help create the structure and hierarchy of your test plan.

9. What are some of JMeter's characteristics?

Ans: Some of JMeter's features include:

  • JMeter is a Java-based tool. As a result, it offers all of the advantages of Java-based programs, including portability, extensibility, and robustness.
  • It contains a record and playback capability that makes writing test scripts simple and quick.
  • JMeter has a variety of listeners that may capture and analyze test data in tabular and graphical formats.
  • It can load test HTTP, HTTPS, FTP, LDAP, TCP, and other protocols.

10. Describe how JMeter works internally.

Ans: JMeter creates numerous threads that make simultaneous requests to a target server to simulate real-world user load. The server's performance is then displayed via tables and graphs.

11. Do we need to know how to code to construct JMeter scripts?

Ans: Script generation with JMeter differs from automated script creation in some ways. A script is often written by recording or utilizing the JMeter UI. Then test parameterization, correlation, and setting of various test parameters.

However, coding is required in some cases and can be accomplished via Beanshell scripting.

12. In JMeter, how are queries sent to the server?

Ans: This is accomplished mainly through the use of Samplers. There are various samplers in JMeter, and the following are a handful of the most regularly used ones:

  • HTTP request
  • Junit request
  • JDBC request

13. What understanding do you have of the correlation?

Ans: It is just a method of enticing data from earlier calls and then providing it as parameters to subsequent queries. It is pretty valuable for simplifying scripting, and the benefit is that it removes a great deal of complexity from the session management process.

14. What is the meaning of the Loop Count in a Jmeter?

Ans: In JMeter, the "Loop Count" is an attribute that you can set within a Thread Group or Loop Controller to control how many times the associated test plan or set of samplers will be executed by each virtual user (thread).

15. What is the Parameterization Process?

Ans: It's a pretty easy technique for parameterizing various forms of inputs. This is useful for users who want to use distinct values.

16. What is the difference between Samplers and Thread Groups?

Ans: The difference between Samplers and Thread Groups are:

  • Thread group: JMeter is the first element in any test plan's thread group. It is an essential feature of JMeter that allows you to specify the number of users and the time it takes to load all of the users in a thread group.
  • Samplers: The sampler generates one or more sample results, which include a variety of attributes such as elapsed time, data size, and so on. Thread groups decide which form of request they need to make using samplers, which allows JMeter to send certain types of requests to the server. The HTTP request, FTP request, JDBC request, and other samplers are examples of valuable samplers.
     

Also see, Html interview questions
 

17. In JMeter, what is the difference between a pre-and post-processor?

Ans: Two types of processors exist in Jmeter, i.e., Pre Processor and Post Processors

  • Pre-Processors run ahead of the main sampler and can change the sampler's scope. PreProcessors are JMeter elements that perform actions before sampler requests are executed in a test scenario. PreProcessors can be used to retrieve data from a database, set a timeout between sampler operations, or generate test data, among other things.
     
  • Following the main sampler, Post Processors apply to all samplers in the same Test Plan scope. They help extract fields from server replies and save them in variables. After a sampler request has been processed, the Post Processors have tested plan elements used to perform specific tasks. These post processors are typically used to extract detailed data from the response of a sampling request. For example, we can remove the value of session variables from an HTTP request and send that value to subsequent requests.

18. What are Pre-processor Elements, and what do they do? What are some of the elements of the pre-processor?

Ans: A pre-processor is a step that takes place before the sampler runs. Pre-processor elements are used to configure the sample request before execution or to update variables that are not extracted from the response text.

Some of the elements of the pre-processor are as follows:

  • Modifier for rewriting URLs in HTTP
  • Modifier for HTTP user parameters
  • Link parser for HTML
  • PreProcessor for BeanShell
     

19. How does the Duration Assertion function within a Thread Group?

Ans: The "Duration Assertion" in JMeter is not associated with a Thread Group directly. Instead, it is an assertion that you can add to individual samplers within a Thread Group to check the response time of those specific requests or actions during a test.

20. What is a JMeter timer, and what are the different types?

Ans: By default, a JMeter thread sends requests non-stop. Timers are used to provide a pause between requests. Constant Timer, Gaussian Random Timer, Synchronizing Timer, Uniform Random Timer, and other Timers are examples of Timers used.

21. What should be the maximum number of threads on a single system?

Ans: It is dependent on the hardware configuration of your system, which includes, among other things, a processor, JVM, and allotted memory -Xmx. The amount of components in your test plans impacts thread counts, such as the number of config items or processors and whether you're running in GUI or Non-GUI Mode.

22. Explain how to use JMeter to perform spike testing.

Ans: Timer JMeter spike Testing can be accomplished by synchronizing. Synchronizing timers block threads until a certain number have been blocked, releasing them all at once, resulting in a sizeable instantaneous load.

23. Is it required to explicitly call embedded resources in JMeter?

Ans: You can stop all embedded resources from being called explicitly. "Retrieve embedded resources" is a checkbox at the bottom of requests. It would grab all CSS, JPG, and other files. It's a fantastic approach to locate resources and broken links in a web application.

24. Explain how you can use JMeter to capture the authentication window's script.

Ans: Scripts are usually captured by the recording.

The Thread group in Testplan comes first, followed by HTTPProxyServer in Workbench.

After that, change your connection setting in IE to localhost in address 8911 as in port and set the port number in the Global Setting box (e.g., 8911). Then, start the HTTP proxy server in JMeter and run your login application.

25. What is the purpose of the Timer in JMeter?

Ans:  JMeter can use a timer to delay the time between each request a thread makes. It is capable of resolving the server's overload issue.

26. What are the advantages of using JMeter for performance testing?

Ans: JMeter has several advantages when it comes to performance testing:

  • It can be used to evaluate the performance of both static and dynamic resources.
  • It can support a higher number of concurrent users than your website.
  • It gives you graphical representations of performance reports.

27. What is the definition of a workbench?

Ans: A workbench is a storage area where you can add components to the test plan if needed. Workbench components aren't saved with the test plan right away. They must be saved as separate test fragments. The HTTP(s) Test script recorder is an essential part of the Workbench because it allows you to record HTTPS requests and then load them to see how quickly they respond.

28. In JMeter, what is a Gaussian timer?

Ans Each user request is delayed for a random period using the Gaussian Random Timer element. Based on the Gaussian curve distribution, it has a random deviation around the Constant Delay Offset.

For Example:

  • Deviation Value: 100 milliseconds
  • Constant Delay Offset Value: 300 milliseconds

29. Discuss Poisson Random Timer.

Ans: JMeter Poisson Random Timer is used to produce and add a random delay before running a sampler, as its name suggests. The Poisson Distribution Function was used to create this timer. The Poisson distributed value multiplied by the defined lambda value and the offset value equals the delay (think) time.

30. In JMeter, what are the various thread groups?

Ans:  Undermentioned are the different Thread Groups in JMeter

  • JMeter's Thread Group (Classic).
  • JMeter's Arrivals Thread Group
  • JMeter has a Currency Thread Group.
  • JMeter's Stepping Thread Group
  • JMeter's Ultimate Thread Group
  • Free Form Arrivals Thread Group.

31. How do you deal with sessions and cookies in JMeter?

Ans: Sessions and cookies in JMeter can be managed using config components like HTTP Cache Manager, which lets you clear cookies after each iteration and add user-defined cookies. The HTTP Cache Manager helps you clean the cache after each iteration, as required in load tests, and limits the number of objects that can be cached. These config elements can be used to set up the HTTP sampler.

32. Why is running JMeter in GUI mode recommended?

Ans: JMeter tests can be run in GUI or non-GUI modes. Because the AWT event thread can kill the tests in high load scenarios, running the load test in Non-GUI mode is highly recommended.

JMeter supports several non-GUI modes, including:

  • Command-line
  • Plugin for ANT
  • Plugin MAVEN
  • Jenkins

33. Is JMeter capable of running Selenium scripts? If so, how should you go about doing it?

Ans: You can run Selenium scripts in JMeter to understand how well they perform.

You can do it in two ways. You can either build selenium scripts with JUnit libraries and save them as Jars, then copy them to the JMeter directory. Then, in your test plan, include the JUnit sampler and import the Jar file.
Otherwise, you can add the Webdriver sampler plugin to the JMeter ext folder. JMeter should be restarted now. In the Webdriver sampler, write your Selenium code and run it to see how it performs.

Learn more about,  Azure Data Engineer Interview Questions here.

34. What is BeanShell scripting, and how does it work?

Ans: BeanShell is a lightweight Java scripting language that JMeter uses to perform some complex tasks. With the help of coding, the BeanShell sampler can perform various tasks. You can get the thread number, run the current sampler, get the cookies, and so on.

35. What is the meaning of a Root CA certificate?

Ans: A certificate is required to authenticate HTTPS connections established when the browser connects to the webserver. JMeter creates it to intercept SSL traffic and record the actions. You must have this certificate on your phone to record activities via mobile.

36. What is Tidy Parsing, and how does it work?

Ans: In the Xpath extractor, tidy parsing is a type of parsing. If the response is pure XML, tidy parsing is not required; however, if the reaction is XHTML, tidy parsing must be enabled to get the correct results.

37. How would you handle dynamic parameters in JMeter scripts to ensure accurate load testing results?

Ans: To handle dynamic parameters in JMeter scripts for accurate load testing results, you need to identify dynamic parameters in the application, extract dynamic values using JMeter's post-processors, Store values in JMeter variables, replace dynamic values with variables in subsequent requests, maintain the session state for proper correlation, validate the script with a small load, and monitor results during load testing and adjust it if required.

38. What is the purpose of the Ramp-Up Period in a Thread Group?

Ans: The purpose of the Ramp-Up Period in a Thread Group in JMeter is to control how gradually or quickly virtual users (threads) are started during a performance test. It determines the pacing at which users enter the test.

Imagine you have a Thread Group with 100 virtual users, and you set a Ramp-Up Period of 10 seconds. This means that over the course of 10 seconds, JMeter will gradually start these 100 virtual users, with approximately 10 new users starting each second.

The Ramp-Up Period is important for realistic load testing scenarios. It simulates a more natural user load buildup on your application, which can help identify how your system handles increasing user traffic. This gradual increase in user load allows you to monitor system behavior and performance as it scales up, rather than hitting it with all users simultaneously.

39. How can you adjust the thread count within a Thread Group configuration?

Ans: To adjust the thread count within a Thread Group configuration in JMeter, follow these steps:

  • Open your JMeter test plan.
  • Locate the Thread Group you want to modify in the Test Plan tree on the left-hand side.
  • Right-click on the Thread Group and select "Edit."
  • In the Thread Group configuration window, look for the "Number of Threads (users)" field. This is where you can adjust the thread count.
  • Simply change the number in the "Number of Threads (users)" field to the desired thread count. This number represents the total number of virtual users (threads) that will be created to simulate concurrent users accessing your application.
  • Save your test plan.
  • When you run the test, JMeter will use the new thread count you specified in the Thread Group.

40. What are JMeter listeners and how can they be used to analyze and interpret test results effectively?

Ans: JMeter listeners are components in Apache JMeter. It is a popular open-source load-testing tool. JMeter listeners provide a range of capabilities to effectively analyze and interpret test results. During test execution, real-time monitoring offered by listeners allows you to track performance metrics. For example, error rates, response times, and throughput.

41. How would you handle performance bottlenecks in JMeter tests and what techniques or strategies would you employ to optimize test scripts and improve performance?

Ans: Handling performance bottlenecks in JMeter tests, you need to requires a systematic approach and various techniques to optimize test scripts and improve performance.

  • Identify Bottlenecks
  • Performance Monitoring
  • Optimize Test Scripts
  • Analyze and Adjust Resource Allocation
  • Use Timers and Pauses
  • Distributed Testing
  • Use Test Data Caching
  • Parameterize Test Data
  • Use Assertions Efficiently
  • Continuous Performance Testing
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Tips

  • We are confident that this article on JMeter interview questions has significantly increased your understanding of JMeter topics.
  • When a recruiter asks a question, it's not just your answer that's recorded. They want to know how you approach the situation and analyze the issue.
  • In short, brushing up on your technical and conceptual skills while remembering these commonly asked JMeter interview questions will help you prepare for your tech interview.
  • You can confidently crack any interview if you have a firm grasp of all the questions presented here.
     

Frequently Asked Questions

What is JMeter mainly used for?

JMeter is a powerful tool mainly used for load testing, performance testing, and stress testing of web applications to measure their performance under different conditions.

Is JMeter easy or tough?

JMeter can be challenging for beginners due to its extensive features, but it becomes easier with practice. Its complexity depends on the complexity of your testing scenarios.

What type of file is a JMeter script?

A JMeter script is typically saved as a ".jmx" file. It contains test plan configurations, samplers, and settings for load testing and performance testing within the JMeter application.

What are the advantages of JMeter?

It's a tried-and-true method that consistently produces error-free results. Its ability to work with all apps makes it the best at what it does. Because JMeter is an open-source tool, users do not have to worry about the cost. It is not difficult to learn and use this tool.
Furthermore, tailoring the JMeter tool to meet specific requirements is not a difficult task. Several tutorials and online communities can assist in resolving any issues that arise during the process.

Which testing is not supported by JMeter?

JMeter does not support native mobile applications or desktop application testing. It is designed for web application testing.

Who mainly uses JMeter?

Software development firms like IBM, Oracle, Capgemini, TCS, and others use Apache JMeter worldwide.
JMeter is a software performance and functionality testing tool. Both static and dynamic resources are stretched with Apache JMeter. For performance testing of web applications, Apache JMeter is widely used.

In Selenium, what is JMeter?

It is possible to integrate both Apache JMeter and Selenium. The Apache JMeter WebDriver plugin is used to use Selenium in Apache JMeter.
Transfer the WebDriver plugin files to Apache JMeter's libs and ext directories. Web browser-specific tests, such as Chrome and Firefox, can be run using the Apache JMeter GUI.

Is functional testing performed with JMeter?

Yes, Apache JMeter can be used to evaluate the functionality and performance of a software application. Both static and dynamic resources are tested with Apache JMeter. For performance testing of web applications, Apache JMeter is widely used.
Because Apache JMeter is free software, users can customize it to meet their specific requirements.

Conclusion

We hope this article on JMeter interview questions has dramatically increased your understanding of JMeter topics. A solid mastery of the questions given here will enable you to crack any interview confidently. And if you would like to learn more, check out our articles in the code studio library

The knowledge never stops; look at more related articles: Angular 8 Interview Questions, Spark Interview Questions, SDLC Interview Questions, Azure Data Factory Interview Questions, Terraform Interview Questions, HR Interview Questions and Answers , and many more.

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