Performance Testing Interview Questions

Developing efficient and high-performance software applications is crucial for improved user experience and smooth running of businesses. Performance testing plays a key role in ensuring the quality and performance of applications. You can measure the responsiveness and stability of applications under various workloads through performance testing.

Many companies evaluate their software products through performance testing to offer better user experiences. That’s why the demand for performance testers is on the rise. Keeping that in mind, we have curated the key performance testing interview questions and answers in this blog to enrich your knowledge of performance testing and breeze through your interviews effortlessly. Let’s begin!

Table of Contents

• Performance Testing Interview Questions
  • Freshers
  • Experienced
• FAQs
• Skills
• Job Responsibilities
• Conclusion

Performance Testing Interview Questions and Answers For Freshers

In this section, I have curated the basic-level performance testing interview questions for beginners. This QA section will introduce you to types of performance testing, performance testing lifecycle, web-based testing, and more. Let’s jump in!

1. What is performance testing?

Performance testing is essentially a type of non-functional software testing. We conduct performance testing to identify performance metrics of applications like stability, speed, scalability, and responsiveness under different workloads. We can also measure the data transfer velocity, maximum concurrent users, network bandwidth, memory utilisation, etc.

For example, performance testing examines how an application responds if a thousand users log in at a time. Also, we can simulate how the application responds when multiple users perform the same activity.

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2. Why is performance testing essential?

• Performance testing is required to identify the performance issues that may arise in software applications. Also, we can remove the bottlenecks or problems before they affect the application performance.
• Performance testing is required to improve the reliability and stability of applications.
• It is important to conduct performance testing to optimise the performance of applications and improve user experience. Simply put, performance testing is required to simulate an application's behaviour under different loads or scenarios.
• We conduct performance testing to verify the application's response time for multiple users.
• We can measure the application stability under both the expected and unexpected loads.
• We can decipher the maximum capacity of applications and transaction quantity.

3. What are the different types of performance testing?

There are many types of performance testing, as listed below.

1. Load Testing: This type of testing is applied when we want to test volume-based applications. We also conduct this testing to determine how the application behaves when varying load levels are applied. This testing helps track applications' responsiveness and stability when the number of users or operations increases.
2. Stress Testing: We perform this testing to examine how applications behave during abnormal conditions or peak activity. This testing helps to measure at what point an application malfunctions or breaks.
3. Spike Testing: This testing helps to identify how an application behaves when there is high-level traffic in a short time. In other words, we perform spike testing to verify the performance of applications if there is a sudden rise in the number of users with the same resources.
4. Endurance Testing: It is also called soak testing. We perform this testing to identify how applications behave under typical workloads but for a long time. This testing mainly helps track memory leaks in applications.
5. Scalability Testing: We conduct this testing to see how an application responds to steadily increasing workloads.
6. Volume Testing: This testing is also known as flood testing. This testing helps identify how an application behaves when loaded with much data. This testing helps to prepare the fail-safe mechanisms for applications to enhance their security. In volume testing, we can test applications to know how much data they can handle during the execution of the applications. We perform this testing when many users accessing the applications concurrently.

[ Learn Performance Testing Tutorial ]

4. What are the key metrics of performance testing?

Following are the important metrics of performance testing.

• Memory: It is a storage space occupied by an application while processing data or performing an action.
• Throughput: The number of data units an application processes at a specific time. This is the server's response to the client's request. We can measure Throughput in different ways, like bits per second, requests handled per day, reports per year, etc. 
• Latency: It is the time between a request sent to an application and when it starts responding to that request.
• Bandwidth: The amount of data passed across a network in a second.
• Speed: It is the time an application takes to load its elements like text, video, image, etc.

5. What are the tools used for performance testing?    

The following are the best tools for performance testing.

• LoadRunner: We use this tool to test the web and various applications. This tool helps to measure the performance of every component of an application and identify bottlenecks.
• Silk Performer: This tool helps to assess the performance of database servers, intranet servers, and middleware. It helps to test systems before they are completely developed. It allows customised testing with virtual users.
• LoadNinja: This tool allows for performing load tests without using scripts. As a result, testing time is reduced drastically. This tool provides insightful reports with which we can optimise applications before any bottlenecks occur.
• WebLOAD: We use this tool to measure the performance of applications that face huge traffic. This tool supports DOM-based recording/playback and automatic correlation.
• LoadView: This tool allows testing web applications, websites, and APIs for varying workloads. It uses the real-browsers for testing to provide accurate and insightful conclusions and recommendations to teams.

6. What is Soak Testing?

Soak testing is also called as endurance testing or capacity testing. We conduct this testing to measure the response time and stability of applications for loads applied on it for a long time. By performing soak testing, we can optimise potential problems such as resource leaks, memory leaks, etc.

Soak testing helps track application performance for a massive load for a long time. It helps to avoid unexpected errors and crashes of applications. Besides, we must conduct soak testing during system upgrades, new software releases, and peak usage periods.

7. What are the phases of the performance test lifecycle?

The different phases of the performance test are given below:

• Design or planning
• Building
• Execution
• Tuning and analysing.

8. Define Performance Tuning.

We perform performance tuning to make improvements in the system's performance. There are two types.

• Hardware Tuning: We make the hardware tuning to add, replace, or optimise components of the hardware of the application system.
• Software Tuning: This tuning is beneficial for identifying the bottlenecks. Profiling a database and software codes plays a crucial role in software tuning. We make software tuning to modify the software to rectify the bottlenecks.

9. What are the entering and exiting criteria for performance testing?

The entry criteria for performance testing are listed below:

• Finalised NFRs
• Readiness of the test environment and test data
• Finalised test plan and test scripts.

The exit criteria for the performance testing are given below:

• Meeting the NFRs
• No performance bottlenecks
• Submission of final performance test report.

10. What are the activities performed during performance testing?

The activities below will be done during the performance testing.

• Creating user scenarios
• Distributing users
• Scripting
• Running applications.

11. What is JMeter?

JMeter is a Java tool that we use to make performance testing. It helps to analyse and measure the performance of various services on a web application. The architecture of JMeter depends on plugins. The latest version of Apache JMeter is 3.3. We can run JMeter along with Jenkins.

[ Related Blog: JMeter Tutorial For Beginners ]

12. What are the steps required in JMeter to create a performance test plan?

We must follow the steps below to create a performance test plan in JMeter. They are:

• Adding a thread group
• Adding JMeter elements
• Adding Graph result
• Running the test
• Getting the result.

13. What are the common mistakes that may arise during performance testing?

Below are the common mistakes that may arise while performing the performance testing. They are:

• Jumping to multi-user tests directly
• Not validating test results
• Short running duration 
• Unknown workload details 
• Lacking long-duration sustainability test 
• Not stimulating network bandwidth
• Ambiguity in concurrent users
• Incorrect extrapolation of pilots 
• Differences between test and production environment 
• Underestimating performance testing schedules
• Inappropriate base-lining of configurations.

14. Can you list the common performance bottlenecks?

The typical performance bottlenecks include:

• CPU Utilization
• Networking Utilization
• Memory Utilization
• Disk Usage.

15. What is NeoLoad?

NeoLoad is one type of load testing tool. We can use NeoLoad to decipher the performance of the web or mobile applications. NeoLoad is a stress and load testing tool. It helps developers to optimise the application performance before it goes into production.

16. What is baseline testing?

We perform baseline testing on applications before coming to any conclusion. It helps decide the actions to take in the next stage of the application. Also, it helps to resolve many issues. It is a baseline that forms the base of any calculation, construction, and measurement.

17. What is distributed testing?

Distributed testing helps perform application testing when many users attempt to gain access to applications simultaneously.

18. What are the main advantages of Windows-based testing?

The following are the two key advantages of Windows-based testing.

• Integration
• Functionality.

19. What are the elements associated with web-based testing?

Below are the elements associated with web-based testing.

• Page text
• Response time
• A graphical user interface
• Broken links in web pages.

20. What is Desktop Testing?

Desktop testing is standalone since it does not depend on the applications executed on other machines.

21. What are the two tools you can use for web testing?

We can use the following two tools.

1. JMeter – it is used for performance and load testing
2. Selenium – it is used for web applications.

22. What are the four bugs of Web testing?

Jotted down are the four bugs of web testing.

1. Issues associated with the application navigation
2. issues related to the usability 
3. Issues associated with the functionalities
4. Issues related to GUI.

23. What is load tuning?

Load tuning is a strategy for improving performance by applying necessary modifications to the software. Developers perform this load tuning based on the load testing reports submitted by the performance testers. Besides this, software tuning is the process of fixing software issues.

24. What is the protocol?

The method of executing predefined instructions to make two systems exchange or interact information is defined as protocol. We use protocols to improve the load and performance of applications.

25. What are the baseline tests?

The baseline test is a method of validating or verifying reports submitted by performance testers. We perform baseline tests before taking any action to improve the performance. Upon completing baseline tests, we can recover most of the issues quickly.

26. What are some commercial testing tools?

Silk Performer, WebLoad, QALoad, LoadRunner, and Rational Performance Tester are a few commercial testing tools.

Cheers! You have gone through the fundamental performance testing interview questions and answers. You might have gained the confidence to quickly dive into the advanced interview questions.

Performance Testing Interview Questions For Experienced

This section will take you through the advanced-level performance testing interview questions and answers. It will help to boost your expertise in performance testing to higher levels. Let’s check it out!

27. Differentiate between baseline testing and benchmark testing.

• Benchmark Testing: This testing helps compare the performance of a system with that of a standard industry system.
• Baseline Testing: In this testing, certain test sets are run to get information regarding performance.

28. How can you correlate and make parameterisation in LoadRunner?

We can correlate the values returned from the server for any request. Parameterisation differs from correlation because parameterisation concerns the static data entered by users.

• Static values: These are the values users enter—for example, passwords, card details, usernames, etc.
• Dynamic values: Servers define these values—for example, session IDs, date values, session states, etc.

29. How can you identify performance bottlenecks in applications?

We can follow the steps below to identify performance bottlenecks in applications.

• Monitor the application metrics closely to identify a bottleneck
• Apply a suitable solution to resolve the bottleneck
• Figure out the root cause of the bottleneck
• Take action to prevent the occurrence of the same issues again.

30. Why do you perform automated load testing?

There are some downsides to performing Manual load testing, as listed below.

• We cannot get accurate results in manual testing
• Manual testing increases the costs.
• Synchronisation is not easy in manual testing.

Automated load testing supports overcoming the above-listed drawbacks of manual testing and efficiently performs load testing on applications.

31. How will you identify performance test use cases for any application?

We conduct testing to measure the performance of every action. We need to consider specific measures to monitor these performance tests.

• Users working on the core functionality of the application
• The number of users trying to access the application concurrently
• Perform operations on databases like CRUD.

32. How can you run Spike testing in JMeter?

In JMeter, we can perform Spike testing with the help of the synchronising timer. In this testing, the threads are jammed by synchronising the timer until several threads have been clogged. The threads are released at once, creating a large instantaneous load.

33. What is performance engineering?

Performance engineering is end-to-end application testing and monitoring by testers, product owners, developers, business analysts, etc. It enables strong collaboration between the different application development and optimisation teams.

The ultimate goal of performance engineering is to meet the user/applications through continuous feedback and tuning. As a result, we can develop more scalable and reliable applications with enhanced user experience.    

34. Differentiate performance testing and performance engineering.

Performance testing is the process of identifying the issues that impact the performance of any application. 

On the other hand, improving the performance of any application is known as performance engineering. In performance engineering, necessary changes, such as architecture, implementation, resources, etc., are applied to applications. These measurements are taken from the performance testing.

35. What are the key elements to consider while conducting performance testing?

We need to consider the following when conducting performance testing.

• Reasons for failure
• Defining new actions responsible for performance changes
• The difference in the measurements with earlier test results.
• Documenting every test result for better analysis, including the aim behind the test, number of users, time taken to complete the test, the scenario used, throughput, response time, graphs and their changes with earlier reports, error detected, possible errors, recommendations, etc.

36. What is a Micro Focus LoadRunner?

Micro Focus LoadRunner is one of the robust performance testing tools with which we can measure the performance of applications. This tool simulates multiple concurrent users' actions and tracks the applications' response times. When the number of users increases, the load increases and the response time decreases. This tool helps identify the maximum number of concurrent users allowed to use the applications simultaneously.

37. What is a Blazemeter?

BlazeMeter is a comprehensive performance testing tool that allows us to test and monitor APIs throughout the SDLC. Moreover, it is a continuous testing platform that can run on any device seamlessly.       

38. What are concurrent user hits in the load testing?

Generally, when many users attempt to access an application, performance degradation can occur. In other words, the performance may decrease when the load increases on an application.

A concurrent user hit is a scenario in which more than one user hits on the same event of an application during load testing. This measurement helps to precisely identify how many users can work in a single application event.

39. What is Dynatrace?

Dynatrace is a monitoring tool that supports monitoring, optimising, and managing the performance of applications. It is a software intelligence platform with which we can get real-time insights into the performance of applications.

We can leverage Dynatrace to measure the performance of complex environments such as Microservices, cloud-native applications, and hybrid IT infrastructures. The main thing about Dynatrace is that it uses the AI engine to measure the performance of applications with accurate and valuable insights.

40. What is Capacity Planning?

Capacity planning is the process of determining the hardware and software required to meet the application requirements. It is an iterative process that ensures the availability of IT resources at the right time.

We conduct capacity planning for applications to work as intended in steady-state and peak usage. Capacity planning includes identifying business requirements, designing, testing, and even future requirements.

41. Why is parameterisation necessary in performance testing?

Parametrisation is the process of converting test values into reusable parameters. We can derive the parameters from variables. Not only variables, we can use text strings, expressions, etc., instead of variables for parameterisation.

Further, we use parameterisation to prevent server-side caching and pass multiple values. We can perform parameterisation in many ways, such as replacing the recorded values in requests with dynamic values, adding test data from a separate file, etc.

42. Why should you make a correlation in performance testing?

Correlation in performance testing helps to compare the performance metrics such as the number of concurrent users, response time, etc. That's because the relationship between these variables significantly affects applications' performance.

Understanding the dependencies between the performance metrics allows us to identify performance bottlenecks, optimise resources, and enhance application performance. On top of that, we can make informed decisions by correlating the performance metrics accurately.

43. Why do you use the rendezvous points in performance testing?

We use rendezvous points to synchronise virtual users from different groups in a test case. It allows tasks to be performed at the same time. Also, we use these points in the test case to develop the same load on the server at specific points.

For example, consider a bank server where we can insert rendezvous points so that 100 virtual users can deposit cash simultaneously.

44. What is the Benchmark in performance testing?

Benchmark is a type of load testing performed on the part of the application with varied loads to monitor performance changes. We can repeat this testing until there is a minor percentage of difference in the measurements taken from the earlier tests.

45. What is the difference between a Correlate graph and an overlay graph?

Correlate Graph: This graph plots the Y-axes of two graphs against each other. The Y-axis of the merged graph is the X-axis of the current graph. The Y-axis of the second graph becomes the Y-axis of the merged graph.

For example, the graph below shows hits per second on the Y-axis and Throughput on the X-axis.

Overlay Graph: The X-axis is common for two graphs in this graph. The left Y-axis of the merged graph is the values of the current graph. The right Y-axis of the merged graph shows the values of the second graph.

In the image below, throughput is the value shown on the left Y-axis of the merged graph. Hits per second is the value shown on the right Y-axis of the merged graph.

Celebrate! You have completed learning all the performance testing interview questions and answers now. Undeniably, you must have gained comprehensive knowledge of performance testing from this blog.

Performance Testing FAQs

1. Is performance testing good for a career?

Yes, performance testing is suitable for a career because it opens up doors of opportunities for testing aspirants. According to AmbitionBox, performance testers earn an average salary of over 6 LPA in India. In the USA, performance testers make 107k USD per year on average, according to Talent. AmbitionBox says TCS, Capgemini, Cognizant, Accenture, Infosys, and other top companies hire performance testers for attractive salaries. These figures show that performance testers will have a rewarding and bright career.

2. How long will it take to learn performance testing?

You can learn performance testing in a short period. MindMajix offers 15 hours of performance training in two modes: live online and self-paced videos. If you choose the live online training, you can learn performance testing in 15 hours. If you select the self-paced videos and watch two videos per day, you will complete the learning performance testing in over a week.

3. Is learning performance testing easy?

Of course! You can learn performance testing quickly. If you are eager to learn and invest your time in learning, then learning performance testing is a cakewalk. MindMajix offers performance testing training with industry-experienced trainers. They deliver the training from the basics to advanced concepts step by step so that learners can get in line with the training ideally.

4. Can I automate performance testing?

Yes, you can automate performance testing. By automating the performance testing, you can measure the speed, reliability, response time, scalability, etc., for fluctuating workloads. Blazemeter and Perfecto are the tools we can use to automate performance testing.

5. What type of test data is used for performance testing?

You need to use the representative data for performance testing so that you can simulate real-time scenarios seamlessly. The testing data should have many varieties and be volume-based.

Skills Required For Performance Testers

Primary Skills

Let's look at the essential primary skills required for performance testers in the following.

• Expertise in any programming languages such as Java, JavaScript, Python, and Ruby.
• Proficiency in developing automated test cases and testing web applications.
• Familiar with various performance testing tools like LoadRunner, WebLOAD, Dynatrace, Gatling, JMeter, Taurus, and AppDynamics to optimise the performance of web services and applications.
• Exposure to tools like SOAP UI to analyse WDSL and create web service XML requests.
• Sound exposure to IntroScope tool to monitor and analyse system performance through load tests
• Familiar with the Selenium testing tool to test web applications and browsers on different platforms
• Strong knowledge of working with SQL servers to connect databases, query data, etc.
• Proficiency in the QualityCenter tool in identifying defects and tracking, reporting, and documenting.
• Comprehensive knowledge of performance engineering, including performance testing lifecycle, performance modelling, and performance tuning.

Secondary Skills

Let's look at the secondary skills necessary for performance testers below.

• Ability to understand user behaviour and requirements accurately
• Knowledge of agile development methodologies
• Exposure to software testing lifecycle
• Knowledge of IT infrastructure resources such as servers, load balancers, networks, firewalls, switches, etc.
• Exceptional communication and collaboration skills
• Excellent analytical and problem-solving skills.

Job Responsibilities of Performance Testers

Job Responsibilities For 1-2 Years of Experienced Candidates

Let’s go through the roles and responsibilities of entry-level performance testers in the following.

• Developing test cases based on application and user requirements.
• Creating test scenarios to create test scripts and set up workload models
• Testing the performance of applications using various performance testing tools.
• Conducting brainstorming sessions with teams, performing root cause analysis, etc.
• Analysing test results, identifying bottlenecks, deriving insights, and reporting to stakeholders
• Conducting regression testing and configuring security setup in databases
• Performing code reviews of UNIX shell scripts that you use to test conditions and identify defects
• Collaborating with consultants, product owners,  and developers to design and develop test scenarios.

Job Responsibilities With 3-5 Years of Experienced Candidates

Let’s read through the responsibilities of performance testers with middle-level experience.

• Develop performance test plans, scripts, and scenarios and execute them effectively.
• Conducting stress, load, and regression  loading to identify bottlenecks and enhance the performance of applications
• Monitoring application performance using cloud-based tools such as Dynatrace, Blazemeter, Grafana, etc.
• Setting up monitoring tools and analysing the performance  metrics to identify potential issues
• Preparing detailed performance reporting, including recommendations for enhancements
• Troubleshooting performance issues by collaborating with architects, developers, and IT teams.

Job Responsibilities With More Than 5 Years of Experienced Candidates

Let's look at the responsibilities of senior-level performance testers in the following section.

• Developing comprehensive test plans, including system design specifications and gathering user/system requirements from stakeholders
• Monitoring and analysing the crucial application performance metrics such as response times, CPU usage, Throughput, network latency, thread counts, hit ratios, concurrent users, connection pooling, and more.
• Conducting performance testing using automated tools like LoadRunner, Apache JMeter, or Gatling.
• Collaborating with architects, developer teams, and others to conduct performance testing and make enhancements
• Recommending changes in codes, configurations, database queries, and IT infrastructure to improve application performance
• Performing capacity planning and performance modelling to predict future requirements for different loads.

Well! You have gone through the skills and job responsibilities of performance testers in this section. It will help you to prepare for the performance tester job interviews and build a prosperous career.

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Conclusion

It's a wrap! We hope this blog has given you a sound understanding of the performance testing of applications. You have become familiar with the skills and responsibilities of performance testers by reading this article. We hope the performance testing interview questions and answers will help you ace your interviews and bag your dream job easily.

If you are looking for professional training to boost your skills, you can opt for MindMajix – a pioneer in eLearning providers. MindMajix offers top-class Performance Testing Training for all learning – no matter your expertise and experience. Ultimately, the training will help you build a prosperous career in performance testing.