JMeter is a versatile and powerful open-source tool for performance testing, load testing, and stress testing of web applications. It offers a range of features, including thread groups, preprocessors, post-processors, functions, and monitoring capabilities. To prepare for JMeter interview questions, you’ll need a comprehensive Interview Questions and Answers guide. KnowledgeHut offers the best software testing courses that cover various levels and aspects of JMeter along with interview preparation tips for beginner to advanced professionals. Additionally, the course covers the tool's concepts, architecture, and practical application of JMeter. By going through this interview guide, one can become well-equipped to excel in their JMeter interviews and advance in their career.
JMeter, commonly referred to as "Apache JMeter," is a graphical, open-source application built entirely on the Java Programming Language. It is made to evaluate and assess the functional behavior of web applications and a range of services under load.
JMeter is currently useful in functional testing, JDBC database connections, Web services, generic TCP connections, and OS native processes. It is primarily used for testing Web applications or FTP applications. To obtain precise performance data for your web server, you can carry out a variety of testing activities, such as performance, load, stress, regression, and functional testing.
Stefano Mazzocchi of the Apache Software Foundation is the person who created and first developed JMeter. It was primarily built to evaluate Apache JServ's performance (currently known as the Apache Tomcat project). Apache rebuilt JMeter to improve the GUI, provide more features, and enable functional testing.
JMeter operates at the protocol level rather than being a browser and rendering HTML pages the way a browser should.
A basic question in JMeter interview, don't miss this one.
Apache JMeter is a Java open-source tool. To utilize Apache JMeter to run load or performance tests, it is possible to use the GUI without needing to know any programming language. Just follow the JMeter manual, and it is easy to start creating API testing scenarios.
Depending on the tests to be run with JMeter, there are currently several Samplers and jobs available either out of the box or through other plugins that can be quickly added using the JMeter Plugins Manager. However, Groovy, which is Apache JMeter's suggested scripting language, can be used to expand the capability. Groovy is adaptable and simple to use.
Although BeanShell programming scripts can be used to create assertions or samplers, most activities can now be completed using JMeter's built-in capability. Regex expertise may be helpful because it may be necessary when writing assertions for a JMeter script.
JMeter is an open-source software used to load functional test behavior and compute the performance of the server or client's application. It is a 100% Java desktop application. It was designed to test web applications, but later it was used to test other applications. The users can test the performance of static and dynamic resources like Perl scripts, Java Objects, files, Servlets, Queries, FTP Servers, and Data Bases.
Yes, having extensive experience in JMeter, where I have tested out Perl scripts, Java Objects, files, Servlets, Queries, and FTP Servers. Have tested using the tool on a group of users delivering requests to a target server. It assembles responses and statistics from the target server and could present the server's or applications' performance through tables or graphs to stakeholders.
I am hereby listing some of the best tools available for Testing:
JMeter, commonly referred to as "Apache JMeter," is a graphical, open-source application built entirely on the Java Programming Language. It is made to evaluate and assess the functional behavior of web applications and a range of services under load.
JMeter is currently useful in functional testing, JDBC database connections, Web services, generic TCP connections, and OS native processes, it is primarily used for testing Web applications or FTP applications. To obtain precise performance data for your web server, you can carry out a variety of testing activities, such as performance, load, stress, regression, and functional testing.
Stefano Mazzocchi of the Apache Software Foundation is the person who created and first developed JMeter. It was primarily built to evaluate Apache JServ's performance (currently known as the Apache Tomcat project). Apache rebuilt JMeter to improve the GUI, provide more features, and enable functional testing.
JMeter operates at the protocol level rather than being a browser and rendering HTML pages the way a browser should.
It's no surprise that this one pops up often in JMeter questions. Performance testing is a procedure that allows developers to compare an application's performance to performance metrics. This testing helps determine whether apps are defective or underperforming. The results of the performance testing show where improvements need to be made. Additionally, it shows if apps adhere to the standards established at the start of the application development process. Simply put, this testing determines whether the applications are ready for production.
Performance testing allows developers to locate any bottlenecks in an application's typical operation and fix them before deploying them into a live environment. These are some of the bottlenecks:
Speed, stability, and scalability are some of the crucial performance criteria that determine how well an application performs. Other performance parameters that can be measured through performance testing include data transfer rates, throughput, network bandwidth, dependability, and workload efficiency.
Additionally, we may test the performance of various applications and compare the results to determine the variables that affect the performance of the applications. As a result, we may optimize apps and enhance their functionality
Load testing ensures that websites function consistently and quickly even under heavy load, evidently following industry standards, and should not crash. This test will also assist us in determining the maximum number of requests that the software system under test can accommodate.
This is because, in this testing scenario, there's an attempt to duplicate a setting that replicates how a user might react in the real world. This replication of human behavior is transmitted via various API calls, sometimes in the form of numerous concurrent queries.
Once this testing process is complete, the bottleneck will finally be revealed, which will cause the performance to deteriorate gradually. The software development team can then begin working on optimizing this after the bottleneck has been located, which will eventually produce the optimal user experience.
Stress Testing, which is a type of software testing, examines how the program behaves in challenging situations. It tests how resilient a system will be, as well as its ability to respond and handle errors in circumstances where its regular operation may be jeopardized.
The information obtained from carrying out stress tests is quite significant. There is always a chance that an excessive number of requests or other circumstances could cause the system to malfunction. It is important to know what kind of response, whether or not our system will recover, and how long it will keep functioning. Understanding operationality is crucial for comprehending the end-user experience.
A test plan is the JMeter script for conducting tests. Thread groups, logic controllers, sample-generating controllers, listeners, timers, assertions, and configuration elements are examples of test elements. All of the actions that run the script are included in a test plan. Everything that is part of a test plan is carried out top to bottom or per the sequence specified in the test plan. The directory level of a test plan is depicted in the figure below:
A Test Plan contains at least one Thread Group. In each thread group, there is a combination of one or more of the following elements – Sampler, Configuration Element, Listener, Logic Controller, and Timer. One or more Pre-processor elements may become each Sampler, and these may be followed by Post-processor elements, Assertion elements, or both.
Expect to come across this popular question in interview questions on JMeter. The initial components of the Test Plan are Thread Group elements. The thread group elements, as their name suggests, manage how many threads JMeter will employ throughout the test. The Thread Group allows us to regulate the following as well:
This is how the thread group control panel looks: 
The Thread Group Panel has the following:
JMeter offers two different kinds of controllers which are the Samplers and Logic Controllers.
A. Samplers: JMeter can make individual server queries using the samplers. They imitate a user asking the target server for a page. For instance just add an HTTP Request sampler to execute a POST, GET, or DELETE on an HTTP service.
Some good samplers include:
B. Logic Controllers: These let users manage the order in which the samplers are processed in a Thread. The order of a request coming from any of a logic controllers which elements can be changed. Some examples of these child elements are:
C. Throughput Controller: The following are the Logic Controllers offered by JMeter:
Configuration Elements allow users to create defaults and variables that samplers can use. They are utilized to amend or add to Samplers' requests. They are executed before any Samplers that are located in the same scope at the beginning of the scope of which they are a part. A Configuration Element can only be accessed from within the branch where it is located.
Below are the Configuration Elements offered by JMeter:
Listeners allow users to display the output of Samplers as tables, graphs, trees, or plain text in some log files. As a JMeter Sampler component is run, they offer visible access to the information about the test cases that JMeter has acquired.
Anywhere in the test, including just below the test plan, can have listeners added. Only elements that are at or below their level will be used to gather data. Below are the listeners offered by JMeter:
Preprocessor Elements: An element that operates immediately before a sampler does is known as a pre-processor element. They are frequently used to update variables that are not extracted from response text or to change a Sample Request's setting right before it executes. Below are the pre-processor elements offered by JMeter:
Post-Processor Elements: After a sampler has finished running, a post-processor is executed. The most frequent application of this component is to process the response data, such as to get a specific value for later use. Below are the post-processor elements offered by JMeter:
The elements of the test plan are executed in the sequence listed below:
Test Plans are often saved in their XML format, so there is no relationship to any specific operating system. Any OS that supports JMeter can execute it.
The execution outcome of each test plan should be checked by at least one listener. Monitor Tests is an example of a listener. With the monitor test, it is possible to check the server performance graph and the status of the sample the monitor receives.
The monitor test plan in JMeter has the following features:
The fields of any sampler or other elements in a test tree can be filled with customized values provided by JMeter functions. Below is a list of some JMeter Functions:
| Type of Function | Name | Comment |
|---|---|---|
Information | threadNum | Get thread number |
Information | SamplerName | Get the sampler name (label) |
Information | Log | Log (or display) a message (and return the value). |
Information | machineName | Get the local machine name. |
Input | StringFromFile | Read a line from a file. |
Input | FileToString | Read an entire file. |
Input | CSVRead | Read from CSV delimited file. |
Input | XPath | Use an XPath expression to read from a file. |
Calculation | Counter | Generate an incrementing number |
Calculation | intSum | Add int numbers |
Calculation | longSum | Add long numbers |
Calculation | Random | Generate a random number |
Calculation | RandomString | Generate a random string. |
Scripting | BeanShell | Run a BeanShell script |
Scripting | javaScript | Process JavaScript |
Scripting | jexl, jexl2 | Evaluate a common jexl expression |
Properties | Property | Read a property. |
Variables | Split | Split a string into variables |
Variables | V | Evaluate a variable name |
Variables | eval | Evaluate a variable expression |
String | regexFunction | Parse previous response using a regular expression. |
String | escapeOroRegexpChars | Quote meta chars used by ORO regular expressions. |
Any field of any test component can be written with functions and variables. An effective test plan should have the following features:
Variable names supplied as parameters will not be set up and variable references won't work because JMeter thread variables won't have been fully set up by the time the functions are performed. As a result, the functions for variable evaluation, split, and regex will not operate. The threadNum function will not function and is not necessary in terms of the test plan.
Distributed Testing in JMeter aids in scaling up the program's ability to produce the required number of threads (users) for the load test. The master-slave architecture is used for distributed testing, and JMeter is installed on each machine and they all interact using the Java Remote Machine Invocation (RMI).
All of the machines (master and slave) in the distributed architecture are connected to the same local network. One of them is given the role of a master, controlling the other machines while the test is being run. The slave machine carries out the master machine's instructions before sending the request to the target server by hitting the application under test (AUT). JMeter – Distributed Testing (Master-Slave) Architecture is an example of a distributed testing architecture.
The points below will assist in creating a master-slave configuration also known as a distributed environment for JMeter:
Regular expressions are used to search and exit text based on patterns. By integrating the pattern matching program, JMeter understands regular expressions or patterns used throughout a JMeter test plan.
As Test Plans are constructed or improved, regular expressions will undoubtedly help save time and attain greater flexibility. When it is impossible or extremely difficult to predict an outcome, regular expressions offer a straightforward way to extract information from websites.
A typical application example of employing regular expressions is obtaining a session ID from the server response. Users can quickly obtain the unique session key if the server returns one by using expressions in the load script. JMeter's Regular Expression Extractor is needed to use regular expressions in a test plan. Regular expressions can be used in any component of a test plan.
The difference between contains and matches, as used on the Response Assertion test element, should be emphasized.
Contains signifies that the regular expression at least partially matches the target, so 'alphabet' contains "phab" because the regular expression matches the substring "phabe."
Matches denote that the entire target was matched by the regular expression. As a result, 'alphabet' is matched by 'al.*t'
This is a frequently asked question in JMeter testing interview questions.
Thread Groups: The fundamental building block of a JMeter Test Plan is a thread group. As implied by the name, a thread group is a collection of threads running the same scenario. This is regarded as the test plan's starting point. Other test components including controllers, samplers, config components, and listeners are stored in thread groups.
While running the test plan, each thread in the thread group will separately execute every component that falls under the thread group. This is the control panel of the thread group element. For instance, if 100 threads were chosen, JMeter will generate and simulate 100 user requests for the test server.
Samplers: Although JMeter enables testing a wide range of protocols, including HTTP, FTP, JDBC, and others; while Thread Group simulates user requests to the server, however, a Thread Group determine the kind of requests ((HTTP, FTP, etc.) it needs to send, and for that it needs Samplers.
JMeter adds samplers as a child of thread groups. These are used to send the server various kinds of requests. Once the server has completed processing the sampler request, JMeter receives the response, which can then be seen and examined in terms of various performance metrics like response time, hits per second, throughput, etc.
The samplers in JMeter may be launched by using the path- Right-click on the Thread Group, then select Add, then Sampler, before selecting the necessary Sampler.
There are two types of processors exist:
Pre-process: Before sending a Sampler Request, the Pre-processor takes some action. Here's a simple illustration: Suppose a user wants JMeter to "spider" across a website undergoing a test, parse links (check all the links on the page), and then return the HTL. Before generating an HTTP request, it is required to add an action to the controller, such as an "HTML link parser."
Post-processor: After sending a Sampler Request, the Post-processor takes some action. A simple illustration: JMeter makes an HTTP request to the test web server (e.g., www.google.com), and it receives a reply. If the server answer contains a mistake, JMeter can be used to terminate the test. To do this:
Configuration Elements can be used to specify variables, allowing Samplers to access data via these variables. Configuration element can only be accessed from the tee node where it was defined. A configuration element will also take priority over a similar configuration element declared in a parent node if it is defined inside a tree node.
The process of adding variables in JMeter that will offer a wide variety of configuration choices for a load-testing script is known as parameterization. For instance:
There are four different data parameterization options:
Correlation is crucial in JMeter, it is the process of obtaining and passing on to subsequent queries the dynamic answer from the server that was received. It is crucial due to the fact that correlation is needed when writing performance load tests for dynamic sites. The script is worthless if it isn't handled properly.
It is important to distinguish between static and dynamic responses from a testing perspective (the data stays the same for iterating requests). Every HTTP web performance test often includes data correlation. Only when evaluating static content sites, such as certain homepages and contacts, may correlation be disregarded. In other situations, correlation handling must be done at some time throughout the test.
Limits often rely on a variety of variables, and JMeter restrictions are no exception. JMeter limitations vary depending on your machine's and network's capabilities, your performance scripts' complexity, the desired number of simulated users, and other factors.
Correlation is crucial in JMeter, it is the process of obtaining and passing on to subsequent queries the dynamic answer from the server that was received. It is crucial due to the fact that correlation is needed when writing performance load tests for dynamic sites. The script is worthless if it isn't handled properly.
It is important to distinguish between static and dynamic responses from a testing perspective (the data stays the same for iterating requests). Every HTTP web performance test often includes data correlation. Only when evaluating static content sites, such as certain homepages and contacts, may correlation be disregarded. In other situations, correlation handling must be done at some time throughout the test.
Listeners are used to observe and examine the Sampler request and answer as tables, graphs, trees, etc. Additionally, there's the option of saving results to a file for later reading. When a load/stress test is running, the sampler result can be gotten without having to wait. The following is a list of listeners:
More listeners include:
The WorkBench just provides a location to temporarily store test items. It has nothing to do with the Test Plan, as its components are not preserved with the Test Plan, so it may be used as a practice area or for short-term storage. It can also be used to load test scripts straight after recording them.
All HTTP(s) queries made by the application to the server are recorded using the HTTP(s) Test Script Recorder. JMeter has to be configured in a few different ways for it to function. The actions taken to record HTTPS traffic are listed below:
Special values known as JMeter functions can be used to fill in fields on any Sampler or other element in a test tree. A function is called like this:
Clear all
Clear all$[__functionName(var1,var2,var3)}Make careful to escape any commas that are present in function parameters with ","
The name of a function is the same:
_functionNamee. For instance, $__threadNumVariable names provided as parameters won't be created and variable references won't operate, variables are referenced as
${VARIABLE}
One of the most frequently posed JMeter interview questions, be ready for it. Timers are crucial for maintaining equilibrium while doing JMeter performance testing. JMeter threads typically execute one after the other without pausing, this may be implausible in nature because a typical user will pause between each action to read or consider, which is called a Think Time, and it has to be included in the script to make it more realistic.
JMeter offers 9 different timer types for use in such activities, and the user may choose the one that best fits the situation:
Constant Timer: This can be used to give time some Think Time in between requests.
The name provided is shown on the tree, and the thread latency is measured in milliseconds here, as 1000 would be inputted for 1 second.
Uniform Random Timer: A random amount of wait time can be added between user requests using the uniform random timer.
The name element's purpose is to provide a name for the timer that will be displayed in the tree. As the name implies, the maximum think time should be specified in Random Delay Maximum, while Constant Delay Offset is an extra millisecond-based variable.
More timers include:
Aggregate Graph: Aggregate graphs enable us to choose the settings for the graph presentation and make it simple to create bar graphs. The resulting data for the graph and table may be specifically saved as PNG and CSV files.
Aggregate Report: The aggregate report displays a distinct table row for each test's variously titled sampler request.
Assertion Results: Sampler's assertions are shown in the Assertion Results section. Note that assertion results should not be used in load or stress tests because they use a lot of CPU and memory resources. It is advised to use it for debugging or functional testing.
View Results in Table: Every sample/request result is displayed in its own row when using View Results in Table. Note that using View Results in Table during a load or stress test will use quite a lot of memory and CPU. It is advised to use it for debugging or functional testing.
View Results Tree: View Results Trees displays the Sampler responses along with their requests in a tree. The View Results Tree should not be used when doing a load or stress test because it uses a lot of CPU and memory resources. It is advised to use it for debugging or functional testing.
More listeners include:
Performance testing is a non-functional testing method where the effectiveness of the application is assessed under anticipated or greater demand. To make sure that the program doesn't crash and replies within a reasonable amount of time under actual demand, it is done before it is launched on a production server.
Some benefits of Performance Testing include:
JMeter script generation differs slightly from conventional automated script creation. A script may often be written by recording it or utilizing the JMeter UI.
Most definitely, Selenium scripts can be integrated with JMeter via the application of support web driver plugins in the following steps.
A staple advanced JMeter interview question, be prepared to answer this one. There is an increased demand by mobile users for better and more efficient applications which is demonstrated by the 5-star rating on high-performing applications compared to low-performing ones. For this reason, the JMeter application has been developed to incorporate features that permit the recording of actions executed during loading a testing process. There are steps to follow in other to record actions on a mobile device using the JMeter app.
JMeter records action requests on mobile applications using the HTTP(S) Recording Script and it possesses features to initiate, establish and execute tests script performance on mobile applications, but first, there is the need for JMeter configuration on the mobile device which could either be an iOS or an Android device.
Configuring JMeter Set-Up:
In Administration mode, launch the JMeter
METER_HOME/bin, Start jmeter.bat or jmeter.sh
Go to the workbench located under the JMeter test plan and include
Recorder for test script of HTTP(S)
Setting Up JMeter on iOS Devices (iPad, iPhone)
On iPad mobile device
Open and Install the certificate file sent - JMeterTemporaryRootCA.crt. This is recommended for use to prevent SSL handshake problems if the iOS application utilizes HTTPS.
Permit the 'trust certificate' option by going to settings, then to general settings, to them about, and to the certificate trust settings. Here, click on the certificate trust button to turn it on.
On iPhone mobile device
Open settings, then, wifi setting, and click on the arrow close to the wifi connection. Locate the HTTP proxy icon, and under it, chose the manual button and input the desktops IP address into the server bar, then enter '2023' in the port field.
Finally, coordinate the business flow and JMeter and commence recording on the mobile application.
Setting Up JMeter on Android Devices
Graphic User Interface (GUI) is a kind of user interface that permits the interaction of users with electronic devices via graphical and audio features like primary notation, in place of UIs that are text-based. Their actions are executed through direct graphical element manipulation.
The JMeter GUI mode works best for the addition, and editing of new configuration features thread collections, and samplers, but, the GUI mode exhausts the available memory and resource materials during the operation of the recorded scripts, therefore, the GUI is not a recommended mode for heavy load testing like the JMeter.
The recommendation to use a non-GUI mode for running JMeter is probably one of the most essential tips to be aware of when using the JMeter application, as earlier mentioned, this is because the JMeter-GUI is not developed to run heavy loads and it consumes a lot of resource features that could be excessively and severely overwhelming for the server, that results in the delivery of false and incomplete information about the test results. It is noteworthy that, the more resources are being consumed by the server, the less load that will be generated in each test session.
It is thus pertinent to be familiar with the process of running the non-GUI-JMeter tests properly to ensure the efficiency of performance testing.
Since the GUI-JMeter mode is used to record, script and debug, it is important to use it before the phase of execution, but the JMeter testing could be smoothly run from scratch in a non-GUI mode.
Here are useful tips on how to convert a GUI to run non-GUI-JMeter performance tests and boost the efficiency of the execution process.
Disable or delete JMeter listeners
As much as possible, it is advised to use few listeners while staying away from the display of real-time results such as the 'View Results Tree'. By creating a high-level listener for the test run, all other listeners can be disabled or deleted from the test plan. This can be done by including a test flag, for example '-l flag' while specifying the name of the jtl file on which sample results will be logged.
For example; jmeter-n-t-my_test.jmx-llog.jtl
Apply Functions in Variables
When operating a non-GUI test, the script variables may be required to be changed every time a test is started, and this can be very challenging since the script has to be opened on the GUI and the parameters edited and the script saved even before running the test via the command line. Hence, it is better to apply certain functions like _time_ or _random_ in the names of the variables to generate a different name on every test run without the need to manually edit the script.
Functions are specific commands created to permit the user to define variables that will replace static values or generate new values at a test run. Functions can be used in several test run fields if it tallies with the format of the fields, for example, a random field can be added to a field that expects a particular number.
Use command lines to override or establish properties
There may be a need to change and rerun a particular test with various settings when adhering to an appropriate performance testing methodology. This can be done by organizing the script parameters into variables and converting them from the GUI before each test run, but again, this is a very challenging task to execute, if each of these tests is to be run in respective non-GUI modes. To solve this problem, the variables need to be defined in terms of their properties.
Monitoring
A major factor that discourages the use of the non-GUI-JMeter mode is its inability to effectively monitor real-time results on the listeners. However, to solve this challenge, certain options like the one that permits an understanding of the running JMeter simultaneously with the non-GUI mode or the configuration of tests to display live results.
In summary, JMeter non-GUI tests are preferred because it is a powerful tool, that helps minimize the challenges encountered with JMeter. Also, almost every tool that can be used on the GUI-JMeter, can be either used via the command line or the properties file of the non-GUI JMeter.
In the case where selenium automation scripts are available, with a ready functional flow, it is possible to integrate them with JMetre into load-testing for reuse instead of rewriting new java-selenium scripts. Follow the outlined steps below to perform this task of using JMeter to run selenium scripts.
For example; selenium-java-$version2023.jar to %JMETER_HOME%/lib/.
A must-know for anyone heading into a JMeter interview, this question is frequently asked in JMeter Interview Questions. To effectively handle sessions and cookies in JMeter, develop a basic short script with the cookie manager of JMeter that will show its capabilities through the following steps outlined below.
To the test plan, include a thread group.
Test plan>Add>Threads>Thread group.
Thread group>Add>Sampler>HTTP request
Provide information for the following fields:
Add a request order that will open the login platform like the HTTP request
Thread group>Add>Sampler>HTTP request
The values required for this include:
Include a reset password page by addition of another HTTP request order page
Thread group>Add>Listener>View Tree Results
Run the script
For every request order, confirm the cookie data bearing in mind that the initial iteration login page request will have no cookies, but all others do and these cookies are found in the request header meaning that they move from the response to the next request order, and not replaced or lost when a new iteration begins.
Another more advanced way of managing cookies is by applying the HTTP cookie manager configuration element. This allows JMeter to either clear or not clear the cookies from one to another iterations.
Cookies may get cleared when a test user behaves like a new user on each iteration. Acting as a new user, therefore, means that no cookies will be remembered by the website of the user.
This can be set up by selecting the clear cookies in each iteration checkbox option in the cookie manager of HTTP, then clearing the already found results and rerunning the script. Next, perform a verification of the login page and make a second iteration request. With this, the cookie will be cleared out when a different iteration is established.
Cookies are preserved and not cleared out when a test user acts like a recurrent and continuous user of the website, and this will mean the user would remember the cookies from the website.
With JMeter, it is possible to create and update CSV files conveniently and easily, and instead of creating the CSV files separately before uploading them for storage, JMeter helps complete the entire process in a single location. The step listed below demonstrates how to read and write CSV files through JMeter and how to store them.
Thread group>Sampler>BeanShell sampler. Here, the java code will be included together with all the prerequisites for the CSV file.
The codes are responsible for the execution of the writing with the variables contained in the CSV file. The code writes the established parameters to a CSV file and each time the sampler is executed, an additional line is included in the CSV file.
JMeter is a very common tool used for load testing that encourages the expansion of its capabilities. JMeter plugins are software features used by JMeter to expand functionalities and input functions. Numerous plugins are existing, which are used to enhance JMeter's functionality, these plugins avail a simpler way of installing and maintaining the execution of JMeter for its clients.
The top-5 JMeter supported plugins include:
Customized Simple Object Access Protocol (SOAP) Sampler
The SOAP is a JMeter custom sampler that functions with or without numerous attachments. The sampler serves as a sender for SOAP requests to web services and allows users to edit, add or delete code attachments.
Performance Server Monitoring Plugins(PerfMon)
The PerfMon plugin is used for the extension of JMeter using the listener performance and monitoring servers, permitting the follow-up of CPU, disks, and network I/Os and servers memory.
JMeter Custom Thread Groups
These custom plugins are used for adding five other thread groups in JMeter. They include:
Flexible Writing File Plugins
This plugin is used to expand JMeter with a flexible listening file which is applied in writing test results into a specifically flexible file format through the JMeter GUI.
Dummy Sampler Plugins
The dummy sampler plugin is known as the most compliant JMeter sampler used to imitate the request orders and responses without the need to run them. This dummy sampler makes it easy to debug post-processors and file extractors.
Other common JMeter-supported plugins are:
There are two different sorts of controllers in JMeter; the Samplers and the Logical controllers which are responsible for driving the test processing phase.
The Sampler controllers
Samplers used in JMeter are:
The Logical Controllers
Definition/ Explanation
How to perform spike testing using JMeter:
The Gaussian timer is a random timer element used in delaying each request made by users for a random period. Based on the gaussian curve distribution, there is a random deviation premised on the constant offset delay. The gaussian timer halts each thread request for a specified and on time, with the majority of the timeframes happening close to the gaussian distribution times value, the specified value, and the offset value.
An example of this is having a deviation of 500 milliseconds and a constant offset delay of 1000 milliseconds. Here, about 65% of the delays will fall between 500 and 1500 milliseconds. This range is obtained by simply subtracting and adding the values (1000-500 and 1000+500) because the gaussian random timer possesses a random deviation that is dependent on the distribution of the gaussian curve about a constant offset delay.
The total delay is the summation of the distributed value of the gaussian curve with a mean of 0.0 and a standard deviation (SD) of 1.0, multiplied by the specified offset and deviation value.
JMeter assertions are values that provide the basis on which they determine what should be seen as a "pass". Assertions are run against samples and subsamples to confirm if values returned to stay in conformation to expected results. They can as well be added to JMeter variables, and the two major reasons for employing the use of assertions are scope and cost in JMeter.
Some of the different JMeter assertion types are outlined below.
JTL stands for JMeter Text Logs and these are results created for use by JMeter test runs. They are often referred to as JTL files by default extension, however, any other extension may be utilized. If greater than one is run via the same name of an output file, the then work of JMeter would be to automatically append new data at the termination of the file.
To view the JTL file, the following step should be followed.
A red notification signifies a failed step, and an explanation for this failure will be included for display by the sampler result.
Test script recorders like HTTP(S) are used to keep a record of every request made by the HTTP(S) to the server from the home application. Before the test script recorder begins to function, certain configurations will need to be made in the JMeter to make it function effectively.
Here are the steps showing the flow of the test script recorder like the HTTP (s) which should be followed.
Recording in JMeter is an initial step to getting started with application performance testing. The recording flow of business speeds up the process of generating test plans, and if this step is neglected, more time will be wasted in an attempt to manually craft requests. Generally, almost every performance GUI-based testing tool provides a method by which the application can record by proxy.
The actions and requests made on a mobile application can be recorded by JMeter using the HTTP(S) Script Recorder. This script recorder possesses specific features to set it up and run the performance test script. The needed action here is to configure JMeter on the mobile device, which varies between an iOS and an Android device.
The addition of the non-Test element in JMeter to the plan setup permits the capturing of network traffic. This can be achieved by right-clicking on this access path;
Test plan>Add>Non-Test Elements>HTTP(S) Script Test Recorder.
This expands the recording capacity of JMeter.
Tips for commencing a recording phase are to ensure there is a good understanding of the business flow and to have all necessary data available and ready. It is advised to clear out the cache and cookies from a frequently used browser.
During the building of a performance test, the importance of using properties and values cannot be overemphasized to keep static values outside the tests, therefore, ensuring that alterations made to these values are all done in one place instead of having to make changes in several tests.
Oftentimes, although a JMeter suite might have been inherited, or the developer had to rush through a creative process, and may have hard coded the values in the tests, meaning that for every alteration made to an endpoint or server name or a payload sampler, then the changes must be made to the static values within the tests.
The need to update tests may also present, or a developer may have decided to update static values together with properties or variables so that subsequently, changes can be made to the input file of each test. This updating process can be exhausting and time-wasting, but since a JMeter test is a simple XML, updates to the tests can be done in an automated manner by parsing the XML and performing a code update.
The Apache's Xerces XML parer comes with the JMeter application, but a user is at liberty to request and select a different parser from JMeter by incorporating a class for a third-party parser in JMeter's classpath and then updating the properties in the jmeter.properties file together with the name of the full class of the parser implementation.
JMeter is used for testing load functionalities and performance measurement. It executed this task by creating a large-scale number of concurrent users in a heavy-load simulation. The performance testing feature of JMeter is an expanded functionality as it was previously designed for basic processes such as test application activities.
The need to use JMeter for performance testing stems from the reasoning that it is a high-capability resource that can load as well as monitor observable performance for various products, regardless of their protocols or servers, which could be HTTP or HTTPS service webers, databases, Message Oriented Middleware (MOM).
Also, the reason for using JMeter as a chosen application for performance testing results from these factors.
Take, for instance, a brand new API that has been created on the REST principles and configured under the ASP.NET interface. An attempt to save this will require the creation and running of certain stress tests for the API to grasp how rapidly it functions and the amount of load supported by it.
The .NET applications currently can be run against web APIs or applications, and the JMeter application operates the endpoints similar to the different media types since the .NET team stopped their cloud-based operation testing services due to poor community adoption.
JMeter can be used for load testing of .net web applications. This is done to know how fast a site will operate when the number of users on it is doubled or multiplied. Assuming the .net application makes use of a "postback" and has given access to the .net security or validation features, the postback here would submit the page to itself and the server will forward some long variables which are hidden to the user
| Features | JMeter | LoadRunner |
|---|---|---|
Easy operability | It is an application tool, used for performance testing from an open source. JMeter requires a java-supported interface, and once java is downloaded, it can be used to upload and run tests from a JMeter script file | This is a costly application used for execution processes that are often complex because, for every user, it generates a thread making the whole task a daunting operation. |
Generating the load
| Load generation using JMeter is till infinity. It creates the ultimate number of loads based on specific requirements.
| It generates a limited amount of loads for load testing. |
Analysis | Newbies and less experienced testers find the ser of JMeter more straightforward, simple, and easy to understand. | The reports generated by the LoadRunner are in the form of raw files and must be analyzed and interpreted by engineers separately. |
Support | The JMeter community is large and offers a wide range of support to its users | Due to the limited number of users, LoadRunner has a small support community system. |
Required skills | It does not require so many skills. JMeter can be used by a tester with absolutely no knowledge of the words entailed about its scripting and coding. | The is a need for accurate scripting skills and knowledge to operate a performance testing process. |
Elements addition | The feature elements can be altered, added, or removed from JMeter without encountering many difficulties. | The enormous difficulty is experienced in an attempt to tweak or alter the features in a LoadRunner due to its advanced complexity. |
Here are a few effective and important tips that will help you crack the JMeter interview questions. The tips and tricks will help you to prepare from basic JMeter interview questions to experience people.
Navigating JMeter interview questions and answers can be tricky, so having a good source during the process is essential.
Different programs on KnowledgeHut include a comprehensive curriculum, unmatched teaching methods, expert instructors & SMEs guidance, and career coaching to help you nail your following tech interview. JMeter interview questions for experience discussed in this article will help you with senior roles and your growing career path.
Quick key focus areas of the training courses for JMeter technical interview questions preparations are:
With sufficient knowledge of JMeter, anyone can apply for the following few jobs:
Computer Programming courses for beginners on KnowledgeHut will help candidates reach the ideal way. There is no denying that learning JMeter opens prospects for professionals in the testing domain. So, if you intend to learn JMeter, pull your socks up and start.
Within the interview, there would be a mixture of general and technical questions. Below are the few points penned down to expect within the JMeter interview. Performance testing interview questions JMeter for experienced professionals can include questions on topics like XML parser, Workbench, Text Script recorder, and more. JMeter scenario-based interview questions are also a common occurrence in these interviews.
General Questions
Expect the hiring manager to ask a little bit about you.
JMeter Technical Interview Questions
JMeter load testing of Java web applications is one of the best tools available for this is Apache JMeter. Thanks to its Java nature, it is free, open-source, and cross-platform. It requires technical expertise, and there are a lot of possibilities to explore and perform with this tool. Here's the best Software Testing training course to improve your programming skills. Feel free to check it out.
JMeter is an easy, portable, powerful, and highly extensible tool. With JMeter, it is possible to test the performance of resources effectively. We can conduct performance within web service or from load testing to volume testing. Metrics are used to know the precise picture of performance testing. On top of all, JMeter provides many plugins to support the testing.
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