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JMeter Interview Questions

September 10, 2017 JMeter Tutorial
JMeter Interview Questions, JMeter Interview Guide, JMeter Interview

1. What is Performance Testing? (Important JMeter Interview Questions)

Performance testing is the measure of application’s response in situations of stress in terms of the number of users, amount of data etc. This type of testing helps to prepare for expected load and understand the amount of load an application can withstand. 

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2. What is the difference between Load, Stress and volume testing?

  • Load Testing: This testing is done to see whether the application is able to withstand expected the number of users or not.
  • Stress Testing: This testing is done by increasing the number of users greater than expected by application or that an application can withstand.
  • Volume Testing: This type of testing is done with a large amount of data. The behavior of the application is monitored when it is loaded with huge data sets.

3. What is JMeter?

Apache JMeter is performance testing tool which is 100% based on Java.

4. What is a Test plan? (Important JMeter Interview Questions)

When GUI of JMeter is launched, it loads with default components: Test Plan and Work Bench. All the components of JMeter script are added in Test Plan.

5. What is a Thread group in JMeter?

Values added to Thread Group define the number of users hitting the application and how the users will be added to the test flow. In Thread group – Number of Threads, Ramp-up period and Loop count play the crucial role in deciding this.

6. What is a Ramp up period?

Ramp-up period tells JMeter that how much time it will take for all threads to be up and running. For example, If the number of users or threads is 100 and ramp up period is 10 in seconds that means it will take 10s for 100 users to be simulated through JMeter.

7. What is the purpose of adding a Thread group?

Performance testing is about simulating users in real time. Thread group helps to achieve same. The number of users mentioned in Thread group will hit the server and get the response back.

8. What is a Sampler?

The sampler are the requests which are created by JMeter. There are the different type of requests that can be created like FTP request, HTTP request, Java Request, JDBC Request etc. Based on the action that needs to be tested such as file transfer, sending the request to API, sending java request, hitting query on databases, respective type of Sampler can be selected.

9. What is a Controller? (Important JMeter Interview Questions)

The controller is used to control the flow of requests. The order in which request needs to hit the server is decided by the controller to which a particular request is added. All the requests inside one controller are tied to that controller and behave as it is expected to behave. If one wants a particular request to be sent in the different order then it should be placed outside it or in a different controller.

10. What are different types of Controllers in JMeter?

There are many types of controllers. Some of the popular ones are as below :

  • Simple Controller
  • Once Only Controller
  • If Controller
  • Loop Controller
  • Interleave Controller
  • Random controller

11. What is a Listener?

Listener comes into action when the script is executed. It listens to the request and response and displays it in a visual manner. It can be understood as a report of the test run. They are very useful to analyze the test run and help to find the root cause of the failures if any.

12. What are different types of Listeners in JMeter? (Important JMeter Interview Questions)

  • View Results in a Tree
  • View Results in a Table
  • Simple Data writer
  • Aggregate Graph
  • Is there any other way to open JMeter other than GUI mode?

13. JMeter can be run in the non-GUI mode using below command in Command prompt

jmeter -n -t <scriptname.jmx>

14. What is the purpose of Timer?

Timers are also known as Think Time in JMeter. They add certain delay to the requests to which they are added. Adding Timer is not mandatory but usually, are added to certain requests that should hit the server after a certain interval. Different type of Timers are Constant Timer, Gaussian Random Timer, Uniform Random Timer, Synchronising Timer etc.

15. What is a regular expression?

Regular expression or Regex are expressions that are created to fetch data dynamically between requests and response. This is done using software that matches the pattern in JMeter. Symbols such as ., $, +, ? to create expression and match string.

16. What are benefits of JMeter above other tools in the market that are used for performance testing?

  • JMeter is open source and one need not pay for its license.
  • It is platform independent.
  • Supports Multi threading
  • No programming skills are required
  • Good Reporting

17. What is a pre processor?

Pre-Processors are set of actions that are executed before the sample request is executed. There are different types of pre-processors in JMeter like BeanShell Pre-processor, JDBC pre-processor, User Parameters pre-processor etc.

18. What is a post processor?

Post processors are set of actions that are executed after the sample request is executed. There are different types of post processors in JMeter like JDBC post processor, Regular expression extractor, XPath Extractor

19. What is distributed testing using JMeter?

As JMeter consumes a lot of memory and the consumption increases with the number of users hence if one needs to test with a large amount of users than the load can be split between different machines. Each machine hits the server with some load. For example, if one needs to simulate the load of 900 users than 3 machines of 300 load each can be used. This is supported by JMeter and that helps us to use ‘n’ number of servers to generate as much load as we want.

20. How can we parameterize data? (Important JMeter Interview Questions)

Variables in Jmeter can be used to parametrize data. Add config element -> User Defined Variables (Right click Thread Group > Add > Config Element > User Defined Variables). The values in a variable is stored by ${}

Format

Name: Var1

Value: ${variableValue}

Ankita has worked on different types of testing like Manual, Automation, Performance testing.  She likes to learn about new tools in market that help to make testing easier and interesting. Testing is her passion due to versatile areas it offers.

About the author

Ankita Dawar author

Ankita has worked on different types of testing like Manual, Automation, Performance testing.  She likes to learn about new tools in market that help to make testing easier and interesting. Testing is her passion due to versatile areas it offers.

1 Comment

Anonymous

March 7, 2018 at 11:09 am

Very helpful tutorial and interview questions.. thanks a lot

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