JMeter is a Java application developed to evaluate the functionality and performance of web applications. Initially limited to testing only web apps, it was eventually expanded to include testing of other functions. As a result, it is possible to test static and dynamic resources with this application. In addition to simulating a great demand on the server or group of servers, it is also used to analyze performance under various load types. JMeter has gained great popularity in the Software Testing industry in a very short time. This post lists the most often asked JMeter interview questions and answers, which will assist you in comprehending the concept and ace any interview better. The following are the top JMeter interview you are likely to be asked:
1. Kindly Describe What JMeter Is In Your Own Words.
JMeter is a Java-based program employed in the performance load testing of client/server applications. Open source software called Apache JMeter is a desktop application written entirely in Java and designed to load, test, and measure the functionality and performance of an application. Its original purpose was to test web applications, but it has now been extended to perform other types of testing.
2. How Does JMeter Work?
On a fundamental level, JMeter functions by simulating visitors to an application or service by permitting users to send HTTP requests to the server. The server response data is then gathered, and the statistical data is presented visually to users via charts and reports. The collected data and generated reports allow users to observe application behavior and performance bottlenecks, providing insight into where application enhancements are required. Unfortunately, JMeter is not a browser, as it only operates at the protocol level and does not support full client or user operations, such as JavaScript rendering.
3. What Are The Advantages Of Utilizing JMeter?
It is a reliable tool that always ensures error-free outcomes. Its interoperability with all applications makes it the most effective at executing its function. JMeter is an open-source program; thus, users do not have to worry about pricing. Learning and using this technology is not difficult at all. In addition, customizing the JMeter tool to meet specific requirements is not particularly difficult. There are numerous courses and online communities that can assist in resolving any problem that arises during the procedure.
4. Describe Samplers And Thread Groups In JMeter.
- Thread group: JMeter is the starting point for thread group items in any test plan. It is an essential component of JMeter that allows you to set the number of users and loading time for all thread group users.
- Samplers: A sampler generates one or more sample results with numerous properties, such as elapsed time and data size. Samplers enable JMeter to submit particular requests to the server; thread groups determine which type of request to deliver with samplers. Some relevant samplers include HTTP requests, FTP requests, JDBC requests, etc.
5. Mention What Are JMeter Regular Expressions?
JMeter effectively interprets regular expressions and patterns used throughout a JMeter test plan. Based on patterns, regular expressions are used to search and manipulate text. Using the pattern matching software Apache Jakarta ORO, JMeter analyzes regular expressions or patterns used throughout a JMeter test plan. Using regular expressions, we may save significant effort and acquire greater flexibility while enhancing the Test Plan. In addition, regular expressions offer a straightforward approach for extracting information from pages when predicting the output is impossible or extremely difficult.
6. How Can You Reduce JMeter’s Resource Requirements?
Here are some ideas on reducing JMeter resource requirements:
- Use non-GUI mode
- Disable all JMeter graphs due to their high memory use.
- Do not forget to remove the local path from the CSV Data Set Configuration if it is there.
- Use as few Listeners as possible; using the -l switch described above, all Listeners can be deleted or disabled.
- Disable the “View Result Tree” listener since it takes a significant amount of memory and can cause the console to freeze or JMeter to run out of memory.
- Save only the info you require.
- Use the fewest possible assertions.
- Instead of utilizing many samplers of the same type, use the same sampler in a loop with variables to modify the sample.
- Don’t utilize functional mode.
7. What Are The Different Kinds Of Processors That JMeter Supports?
Pre-Processor and Post-Processor are the names of the two primary categories of processors found in JMeter. Post Processors run after the main sampler and apply to all samplers within the same scope of the Test Plan, but Pre-Processors run before the main sampler and can modify the sampler’s scope. Pre-Processors can also change the scope of the sampler. They are useful for extracting certain information from the server response and storing those fields in variables and can be utilized in various contexts.
8. What Exactly Is Performance Testing? And What Are Some Of The Advantages Of Using JMeter For Performance Testing?
Performance Testing is the practice of testing the performance of applications under increased load. It is nonfunctional testing, typically performed before classifying an application as production-ready. It ensures that the application will function properly under all conditions and will not crash under actual demand. Therefore, monitoring performance is a crucial duty.
JMeter offers advantages for performance testing, including:
- It is used to test performance for both static and dynamic resources
- It can manage more concurrent users than your website can handle
- It gives graphical analyses of performance statistics.
9. In JMeter, What Exactly Is A “Test Plan”?
A Test Plan specifies and organizes how and what to test. For instance, the web application and client-server application. JMeter serves as a container for executing tests. A comprehensive test plan will include thread groups, logic controllers, sample-generating controllers, listeners, timers, assertions, and configuration elements. And it also must contain a minimum of one thread group.
10. How Exactly Do You Take Care Of JMeter’s Sessions And Cookies?
Cookies and sessions are managed in JMeter by using config elements like the HTTP Cache Manager. This element allows removing cookies at the end of each iteration and also makes it possible to add cookies defined by the user. The HTTP Cache manager not only assists you in clearing the cache after each iteration following your requirements during the load testing, but it also places a cap on the total number of pieces one can save in the cache. These configuration parameters may be joined together and applied to the HTTP sampler.
11. What Are The Critical Steps In Testing A JDBC Request?
First, JDBC requests establish a connection with databases and measure the query response time.
Important testing procedures for JDBC requests include:
- Setting up Config Element, JDBC Connection setup, including adding Database URL and JDBC Driver Class based on the utilized database. Add the variable name for this connection setting so the sampler can use it.
- Add JDBC Request. Add the same variable name above, and then compose your test queries.
12. What Are The Numerous Protocols That JMeter Supports?
JMeter employs Web protocols, including HTTPS and HTTP, for testing web applications. Rest and SOAP are supported by JMeter when it comes to testing service applications. In addition, it supports HTTP and JDBC for examining the database’s applications. Lightweight Directory Access Protocol is another typical protocol supported by JMeter (LDAP). JMeter is also compatible with the protocols for testing mail servers, such as IMAP and SMTP.
13. What Does Master-Slave Configuration Mean In JMeter? What Is The Configuration Procedure?
Master-slave configuration is a component of distributed testing in which multiple machines perform load testing on the evaluated server. All machines must be on the same network and have the same JMeter version. In distributed testing, one machine is designated as the master, and the others are configured to serve as enslaved people. The procedure includes:
- Edit the JMeter properties file on the master system and add the IP addresses of the slave machines to the remote host column.
- Save the file and then reopen JMeter.
- Now, pick Remote Start from the Run menu in JMeter and enter the computer’s IP address to be invoked.
- Select Remote Start all from the RUN menu to start all slave machines for testing.
14. Describe The Ramp-Up Phase.
When evaluating the loading of an app, just a small number of users are evaluated to investigate the program’s behavior effectively. The Ramp-up phase also provides a wealth of information regarding the application’s general performance. However, it takes some time to make all the users operational. This period is commonly referred to as the Ramp Period. It differs from other applications based on the total number of users, data, and other aspects.
15. What Do You Specifically Know About A Workbench In JMeter?
When working with the tasks in Jmeter, you frequently need a place to store the test pieces. Workbench serves as a short-term storage facility for all of them. In addition to the items that are tested, it also contains several elements that are not tested. This application comes with a browser that makes simply customizing these items easier. Simply because something is kept on the Workbench does not necessarily mean it is permanently retained in the memory.
16. What Are Listeners?
Listeners provide a means by which the results of Samplers can be viewed in various log files as tables, graphs, trees, or even as plain text. They offer a graphical interface for accessing the information that JMeter has acquired about the test cases while the Sampler component of JMeter is being run. It is possible to add listeners at any point during the test, including directly under the test plan. They will only collect data from elements on the same level as them or lower.
17. What Types Of Listeners Are Available Within JMeter?
Listeners store the execution results of load testing in many formats, such as a table, a graph, a tree, or any other structure that may be shown to the client. JMeter includes various built-in listeners; numerous others can be imported using plugins.
Some inbuilt listeners include:
- View results in table format
- View results in tree format
- View graph results
- View aggregate graph
- View aggregate report
- View assertion results
- View response time graph
18. In JMeter, What Exactly Is A “Test Plan”?
A Test Plan is a document that specifies and lays out how and what should be tested. For instance, there is the client-server application and the web application. It is possible to think of it as a container for test procedures. A comprehensive test plan will include at least one component, including but not limited to thread groups, logic controllers, sample-generating controllers, listeners, timers, assertions, and configuration elements. At the very least, one thread group is required for a test plan.
19. Is It Possible For JMeter To Record Actions From Mobile Devices? If Yes, Then How?
Yes, JMeter can record HTTP or HTTPS requests made by your mobile application to the server. However, the mobile device and JMeter must be on the same network. The required configuration is shown below:
- Configure your proxy server to run on a particular port in JMeter.
- Configure the proxy on your mobile Wi-Fi settings, using the same port number as the recorder.
- Install the Root Certificate Authority on your mobile device.
- Send server requests from your mobile device and witness the selected controller capturing them.
20. Is It Possible For JMeter To Execute Selenium Scripts? If Yes, Then How?
It is possible to evaluate the performance of selenium programs using JMeter. There are two methods available. You can utilize JUnit libraries to develop selenium scripts and store them as Jars, or you may copy the Jars into the JMeter directory. Then, include the JUnit sampler in the test plan and import the Jar file. The Webdriver sampler plugin can be put in the JMeter external folder if necessary. Start the JMeter again. Write your Selenium code in the Webdriver sampler, then run it to evaluate its performance.
21. Kindly List Some Of JMeter’s Features.
The following are some of JMeter’s features:
- It is an open-source application.
- The interface is straightforward and intuitive.
- JMeter can load and test the performance of numerous server types: Web – HTTP, HTTPS, SOAP; Database – JDBC, LDAP; Mail – POP3
- This tool is platform-independent.
- Full Swing and lightweight component support are provided.
- The test plans of JMeter are stored in XML format. Therefore, you can use a text editor to construct a test plan.
- Its comprehensive multithreading architecture permits concurrent sampling by multiple threads and simultaneous sampling of distinct functions by independent thread groups.
- It can also be utilized to perform automated and functional application testing.
22. What Characteristics Do Configuration Elements Possess?
Configuration components are responsible for creating all sampler variables and default values. Configuration components can accomplish this if it becomes necessary to modify the sampler’s request. In addition, it simplifies Java testing by establishing default values. When it comes to configuring multiple user logins for websites, configuration components are extremely useful. It is also possible to define default settings utilized by the HTTP controller.
23. What Components Comprise A Thread Group?
The principal Thread Group components include:
- Controller: It is the entity that controls the overall thread group flow.
- Assertion: It is accountable for time management. Essentially, it determines whether the response arrives within the allotted time or not.
- Sampler: Its purpose is to send various requests to the server.
- Configuration elements: It controls data about requests to be integrated with samplers.
- Listeners: Its mission is to preserve the ultimate result of the run.
24. What Language Is JMeter Written In?
Java is used as the programming language for Apache JMeter. Apache JMeter evaluates performance via the execution of test programs. Apache JMeter GUI minimizes the coding required to create a test plan. With Apache JMeter GUI, very little Java programming code is required. Apache JMeter evaluates the functionality and performance of a software application. Apache JMeter tests both static and dynamic resource performance. Apache JMeter is commonly employed for web application performance testing.
25. Is JMeter The Best Tool For Load Testing?
JMeter has been one of the most popular open-source load testing tools for a very long time, making it one of the most familiar performance testing tools for developers and software development teams. In addition, JMeter’s longevity on the market has resulted in abundant documentation, community support, and best practices for its use. Coupled with the fact that it is free, open-source software, it is a compelling choice for teams and organizations from a financial aspect, as it requires few resources to get started.
Conclusion
This completes our article on JMeter interview questions. This interview falls under the difficult category, therefore, you should be well prepared. I hope that these interview questions are helpful for your next interviews. I’m confident that these 25 JMeter interview questions significantly enriched your understanding of JMeter topics. A thorough comprehension of all the questions will enable you to pass any interview on JMeter confidently.
