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Top 30+ Jmeter Interview Questions Guide

April 14, 2017 JMeter Tutorial
jmeter interview questions, jmeter testing,jmeter tool, Jmeter Interview

Jmeter tool is one of the most accepted tools in software testing as its capability to perform both functional & performance testing. Above all JMeter is open source and easy to learn. Here at HelpingTesters, we have come up with 30+ most widely Jmeter interview asked questions with their answers. 

JMeter Interview: JMeter?

A: JMeter is an open source desktop java application used as performance testing tool and designed to measure the performance of web application.

JMeter Interview: What is Performance Testing?

A: Performance Testing is done to find out whether an application is meeting given performance expectation under a given configuration of infrastructure and to know how the system is performing under given condition.

JMeter Interview: What is Load Test?

A: This test is basically used for testing the system under the maximum load it was designed to operate under and find the point where the performance of the system starts degrading.

JMeter Interview: What is Stress Test?

A: This test is done with an intention to break the system thus allows to find out the maximum capacity of the system of the system under given condition thus allowing one to find out the way to overcome it if such requirement to operate in more heavy load, arises in future.

JMeter Interview: What are the Protocols Supported ByJMeter?

A: Following are some of the protocols supported by JMeter.

  • Web Protocol: To test the web applications, it supports both HTTP and HTTPS protocols.
  • Web Services: To test web services applications, it supports both SOAP and REST.
  • FTP: File Transfer Protocol provides the support for testing the FTP servers and applications.
  • Database via JDBC: used for testing the database applications.
  • LDAP: Lightweight Directory Access Protocol.
  • Message-oriented middleware (MOM) via JMS
  • Mail: used for testing of mail servers such as SMTP(S), POP3(S) and IMAP(S)
  • MongoDB (NoSQL): it is recently supported protocol by JMeter.
  • Native commands or shell scripts
  • TCP

JMeter Interview: Explain JMeter Test Plan

A: It is the top level body of JMeter which explains a sequence of steps to be executed at run time. A complete test plan will contain many elements such as one or more thread group, Sampler, Logic controllers, listeners, Timers, assertions and configuration elements. At least one thread group should be there in a test plan. Each sampler can be preceded by one or more Pre-processor elements, followed by Post-Processors and Assertion Elements.

Q. What is Thread in Jmeter?

A: Threads are beginning or the first element in a test plan. It represents a number of Virtual Users which simulate real-time user load on the target server.

JMeter Interview: What Is A Thread Group?

A: It is the initial stage of Test Plan. It represents a group of threads i.e. group of users. Each thread represents one virtual user using the application under test. Each virtual user simulates one real user load to the target server.The controls for thread group allows one to set a number of threads (i.e. Virtual users) for each group to simulate a load of a real user for the set number of threads to a target server. It is mandatory to have at least one thread group in the Test Plan.

JMeter Interview: What is Response time in JMeter report?

A: The Response time is the total elapsed time from the moment when a given request is sent to the server until the total response is returned to the client.

JMeter Interview: What are Samplers in JMeter?

A: Sampler facilitates JMeter to deliver many types of requests to the server. Types of request may be FTP request/HTTP Request/JDBC Request/ etc.

JMeter Interview: What are the main Parts of Thread Group? Please mention along with their roles.

A: Following are the parts of a thread group.

Sampler: It is used for sending various types of requests to the server.
Listeners: It saves the results of the test execution and can be viewed.
Timer: It is used to insert delays between the requests to simulate real traffic.
Controller: It is used to control the flow of the thread group.
Config Element: It contains information about the requests to be added to work with samplers.
Assertion: To check and validate the response.

JMeter Interview: What are Logical Controllers and its types?

A: Logical Controller defines the order of processing request in a Thread.

Some of the types of Logical Controller are: Recording Controller, Loop Controller, Simple Controller, Random Controller and Module Controller.

JMeter Interview: Explain what is configuration elements?

A: It is a simple element where we ca collect the required information for all the samplers i.e. Webserver Hostname, DB URL, any constant etc.They are executed at the start before samplers execute.They are used to add or modify requests made by the sampler.

JMeter Interview: Explain parameterization in JMeter?

A: Using Parameterization we can execute one test plan for more than one user at the same time. This is a method of generalizing an action for many users.

JMeter Interview: Which JMeter elements are used for Parameterization? Mention the steps.

A: Configuration Element is used in Parameterization

Steps are given as below:

Right Click on thread–> Add–>Config Element–> CSV Data Set Config.

JMeter Interview: What Are Listeners?

A: Listener facilitates the viewer to view sample results in different forms i.e. tables, graphs, trees or simple text in some log files. In simple word, Listener is used to showing result of test execution.

JMeter Interview: List Out Few JMeter Listeners.

A: Some of the important JMeter Listeners are as follows.

  • Spline Visualizer
  • Aggregate Report
  • View Result Tree
  • View Result in Table
  • Monitor Results
  • Distribution Graph (alpha)
  • Bean Shell Listener
  • Summary Report
  • Aggregate Graph
  • Assertion Results
  • Backend Listener
  • Comparison Assertion Visualizer
  • Generate summary results
  • Graph Results
  • JSR223 Listener
  • Mailer Visualizer
  • Response Time Graph
  • Save responses to a file
  • Simple data writer

JMeter Interview: Explain what are Pre-processor Elements?

A: Pre-processor is an element which will run before sampler executes. To modify the setting of the sample request just before its execution or to update variables that are not extracted from response text, pre-processor elements are used.

JMeter Interview: List some of the pre-processor elements?

A: Some of the pre-processor elements are:

  • BeanShell PreProcessor
  • BSF PreProcessor
  • HTML Link Parser
  • HTTP URL Re-writing Modifier
  • JDBC PreProcessor
  • JSR223 PreProcessor
  • RegEx User Parameters
  • Sample Timeout
  • User Parameters

JMeter Interview: What is the execution order of Test Elements?

A: Following is the execution order of the test plan elements:

Configuration elements
Pre-Processors
Timers
Sampler
Post-Processors
Assertions
Listeners

JMeter Interview: What are regular expressions in Jmeter?

A: Regular Expression is the special sequence of characters that help you to match or find the string or set of strings in the response of the request.

JMeter Interview: why regular expressions extractor is used in JMeter?

A: In some situation, when one is required to extract the response from one request and pass it to another request, regular expression extractor is used.

JMeter Interview: Explain The Basic Workflow Of JMeter?

A: JMeter simulates group of users to send requests to a target server. It collects response from target server and other statistics which depict the performance of the application or server via graphs or tables.

JMeter Interview: What Is displayed after JMeter window opens?

A: JMeter screen displays the Test Plan and Workbench tabs.

JMeter Interview: What Is Spike Testing And How Can We Perform It In JMeter?

A: Suddenly increasing the number of Virtual users at some point of application and then monitoring its impact on the application, is Spike testing. It is done to check whether application performance is stable or decreases with sudden increase in load.

JMeter Interview: Explain What Is Assertion In JMeter? List Its Types.

A: Assertion plays an important role in testing. It allows one to check whether an application is returning expected data or not.It puts validation on the response of the request made using samples.

JMeter Interview: What are timers and what are the different timers available?

A: By default, JMeter keeps on sending requests without pausing between each request, which is quite impractical. In order to simulate real traffic, JMeter provides timer element so as to have some delay between the requests.

There are many timers available in JMeter which are Bean Shell Timer, BSF Timer, Constant Throughput Timer, Constant Timer, Gaussian Random Timer, JSR223 Timer, Poisson Random Timer, Synchronizing Timer, and Uniform Random Timer.

JMeter Interview: What is throughput in the JMeter listener?

A: Throughput is the number of requests per unit of time(seconds, minutes, hours) that are sent to your server during the test.

JMeter Interview: How to handle correlation in JMeter?

A: To understand the correlation, it is important to know that server sends dynamic content each time it gets the request and that dynamic content is used in the subsequent requests. This dynamic content changes each time user sends the same request. So, one recorded script will not work for sending the same request to the server. For, server to accept this dynamic value,

Correlation is done which takes left boundary and right boundary of the dynamic value, which makes it feasible to run the same script again and again, after correlation is done.

For correlation in JMeter, we use the “Regular Expression Extractor” which makes use of regular expressions.

About the author

Vaibhav Singhal author

Vaibhav is in software testing since a decade. Worked with different testing techniques along with exploratory testing. Performed different regression, performance, api etc testing with tools and libraries like selenium, jmeter, loadrunner, protractor, rest assured, Katalon Appium and others.

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