Performance Testing Interview Questions

Explain Performance Testing.

Performance testing is a basic software testing service to test an application for all performance bottlenecks. It also becomes a QA effort to check the performance of an application with varied user loads. As an effort of non-functional Testing, the performance testing addresses the pain points experienced by end-users in real-time, like application or website crashes, application load time, etc. Performance testing also includes many other complex aspects, but that's a good point to start.

What is the purpose of performance testing?

Performance testing is a basic software testing service to test an application for all performance bottlenecks. Before and after the release of a product, the performance tests make it possible to assess the pain points of users through monitoring, analyzing and effectively managing the performance of the entire application. The robustness of an application is enhanced by efficient performance testing in order to avoid losing the trust of the users.

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What are the types of Performance testing?

The various types of performance testing include:

Load Testing: It verifies the ability of the application to work with the intended user loads. The purpose of load testing is to identify bottlenecks prior to the implementation of the software application.

Stress testing: It is an application testing with extreme workloads to check how it manages high traffic or data processing. The purpose of stress testing is to determine the breaking point for an application.

Endurance Testing: It is performed to ensure that the software can manage the expected load for a long period of time.

Spike testing: It Tests the software's response to sudden large spikes of user-generated load.

Volume Testing: In Volume Testing, a large amount of data is entered into a database, and the general behaviour of the software system is monitored.

Scalability Testing: The purpose of scalability testing is to find out the effectiveness of the software application at scale to support user load increase.

List out some common performance issues experienced by users?

The following are some common performance issues that users face:

• Poor scalability
• Poor Response time
• Long loading time
• Bottlenecking (like hardware issues or coding errors)

List some of the commonly used performance testing tools.

There are many tools in the market for test management, GUI testing, performance testing, functional Testing, etc. Choosing the tool that is on-demand, easy to learn, generic and effective for the kind of test required. Following are some of the common performance testing tools:

• JMeter
• HP Loader
• Proxy Sniffer
• HTTP Load
• Borland Silk Performer
• Rational Performance Tester

Mention a few performance bottlenecks.

The following are a few common performance bottlenecks:

• Disk Usage
• S limitation
• Memory Utilization
• CPU Utilization
• Networking Utilization

What parameters are taken into consideration for performance testing?

The performance tests are based on the following parameters:

• Top waits
• Bandwidth
• Memory usage
• Memory pages
• Response time
• Thread counts
• Processor usage
• Committed memory
• CPU interruption per second
• Network output queue length

What factors influence the selection of performance testing tools?

What does the performance testing process include?

The performance testing life cycle involves the following steps or phases.

Right testing environment: Understand the physical test environment prior to performance testing, such as software, hardware and network configuration.

Determine performance acceptance criteria: It includes goals and constraints of throughput, resource allocation and response time.

Plan & design Performance testing: Specify the way usage may vary between end-users and identify key scenarios for testing all the potential use cases.

Test environment configuration: Prior to execution, prepare the test environment and organize tools, other resources, and so on.

Test Design Implementation: Depending on your test design, build a performance test.

Run the test: monitor and execute the tests.

Analyze, tune and retest: Review, consolidate and share the test findings. Then, fine-tune and retest to see whether there is an improvement in performance. Stop the test if there are bottlenecks in the CPU.

) What is throughput?

Throughput refers to the quantity of data being transported to the server in response to the client's request at a particular time. It is calculated according to requests per second, reports per year, calls per day, visits per second, etc. Application performance is based on the throughput value, so the higher the throughput value, the higher the application performance.

Intermediate level Performance testing interview questions:

) How does benchmark testing differ from baseline testing?

Benchmark testing: This is the method of comparing the performance of the system performance tuning against an industry standard which is established by other organizations.

Baseline Testing: This is the process to execute a set of tests for capturing performance information. When future changes to the application take place, this information serves as the reference.

) What are the differences between Functional Testing and Performance testing?

Functional Testing: It verifies the accuracy of software with inputs defined with respect to expected outputs, and functional tests are carried out. It can be carried out manually or automatically. Here only One user carries out all operations. Tester, development and Client involvement is necessary for functional Testing. A production size test environment is not required, and the H/W requirements are minimum. 

Performance testing: the performance tests are performed to validate how the system behaves under different load conditions. It provides the best outcome when automated. More than one user carries out the desired operations. Tester, Customer, DBA, Developer, & N/W Management Team are involved in performance testing. It needs to be close to the production test environment and multiple H/W facilities to complete the load.

) What is Spike testing and Endurance testing?

Spike Testing: This is a kind of performance test which is performed for analyzing how the system behaves when the load is significantly increased.

Endurance Testing: This is a kind of performance testing that is intended to assess the behaviour of the system when a large workload is provided on an ongoing basis.

) What advantages does LoadRunner have when it comes to testing tools?

Following are some of the advantages of LoadRunner:

• Versatility
• Robust reports
• Easy Integrations
• Test Results
• Enterprise Package

) What are the various phases of automated performance testing?

The automated performance testing phases include the following:

• Designing or Planning
• Building
• Execution
• Analyzing and Tuning

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) What activities are involved with performance testing?

The activities associated with performance testing are:

• Gathering the requirements
• Selecting tools
• Plan of performance test
• Development of performance test
• Modelling performance test
• Test execution
• Analysis

) List some common mistakes during performance testing?

Following are some of the common mistakes in performance testing:

• Jump directly to multiuser tests.
• No validation of test results.
• Workload details are unknown.
• Very little execution time
• No long-term sustainability test.
• Confusion about the definition of concurrent users.
• Insufficient data population.
• Significant difference among production and test environment
• Non-simulated network bandwidth.
• Underestimation of performance testing schedules.
• Inaccurate extrapolation of pilots.
• Improper baselining of configurations.

) What is meant by Concurrent user load?

Concurrent user load is defined as something if more users hit any of the operations and functionality simultaneously. Concurrent user load tests simultaneously send artificial traffic to the web app to focus on the infrastructure and the record system response times over periods of sustained high load.

) What is performance tuning?

) What is soak Testing and Stress Testing?

Soak Testing: Soak Testing is a type of performance test which checks the stability and performance characteristics of a system over a prolonged period of time. System resources are checked, and their performance is impacted by the increased load.

Stress testing: Stress Testing is a software testing activity which determines the robustness of the software through Testing beyond the limitations of normal operation. Performance results will be analyzed to determine the extent to which resources can maintain the upper bound with good performance as intended.

Performance testing interview questions for Experienced:

) How can we identify the performance bottleneck situations?

Performance Bottlenecks are identified through application monitoring against stress and load conditions. To identify a bottleneck situation in performance testing, the testers generally use Load Runner since it supports various kinds of monitors such as a network delay monitor, run monitor, web resource monitor, firewall monitor, database server monitor, and Java performance and ERP server resource monitor. These monitors will help the tester determine the conditions that result in the application response time increasing.

) What is the difference between manual and automatic Correlation?

Correlation is used for dealing with dynamic values within a script. Dynamic values vary for every user action when the action is replayed by the same user or any other user. In both cases, the Correlation deals with these values and will prevent them from failing when executed. Manual Correlation implies the identification of the dynamic value, the search for the first occurrence of the dynamic value, identify the unique limits to capture the dynamic value, write the web_reg_save_param correlation function prior to the request with the first dynamic value occurrence in its response.

Automated Correlation is based on the predefined correlation rules. The script is replayed and scanned for autocorrelation in case of failure. Vugen identifies where correlation rules work and correlates the value over approval.

) What are the reasons for discontinuing manual load testing?

A number of disadvantages of manual load tests have led to the adoption of automated load tests. Some reasons are as follows:

• Complex procedure for accurately measuring application performance.
• Complicated synchronization procedures involving two or multiple users.
• Difficulty in assessing and identifying outcomes and bottlenecks.
• Increase in the total cost of infrastructure.

) How can we perform Spike Testing on JMeter?

In JMeter, spike testing can be performed with the help of Synchronizing Timer. Threads are blocked by synchronizing the timer till a particular number of threads are successfully blocked and then released immediately, creating a large immediate load.

) What is profiling?

Profiling is a process that identifies a bottleneck at minimum levels. It consists mainly of performance testers or developers and is performed by presentation teams for manufacturing. We may create a profile within any application layer that is tested. To perform application profiling, we may need to use tools to profile the performance of application servers.

) What are the entry and exit criteria for the performance testing?

Performance testing only starts at a design level. Over the entire lifecycle development process, the performance tuning is performed, and the factors underlying it are reliability and scalability when the load is present, application release time as well as performance and stress tolerance criteria. Once the test is complete, the results are then collected and analyzed for making performance improvements.

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) What are the various components that makeup LoadRunner?

The most important components of LoadRunner are:

VUGen: Saves Vuser scripts which mimic the actions of true users.

Controller: Administrative centre for the creation, maintenance and performance of load test scenarios.

Load Generator: An agent that enables us to generate load.

Analysis: offers graphs and reports that provide a summary of system performance.

) How steps are validated in a script?

) How can we identify the use cases of performance testing in any application?

Some measures should be taken into account when monitoring performance tests. 

Users need to work with the main features of the application, attempt to carry out database operations such as CRUD, and There should be more users attempting to access the application at the same time. Along with all of the above criteria, manual test cases may help us to identify performance measures.

) What is an Overlap graph and Correlation graph?

Correlate Graph: Y-axis is plotted in relation to each other. Subsequently, the Y-axis of the active graph is treated as the X-axis of the merged graph. Now, the graph which has been merged with the Y-axis of this graph becomes the merged Y-axis.

Overlay Graphic: Draw two graphs that contain the same x-axis. The left y-axis of the merged graph indicates the current value of the graph. The Y-axis to the right indicates the value of the Y-axis of the merged graph.

) Define Distributed Testing?

Ans. It is a process of testing applications when many users attain application access through multiple systems/devices.

) What is meant by Load Tuning?

Ans. Load tuning is a method to improve performance through necessary changes to software configurations. Developers can execute this based on the load testing results submitted by performance testers.

) What is meant by Protocol in performance testing?

Ans. The Protocol is a predefined set of rules that helps to exchange information between two or more devices. The use of protocols improves the application’s loading and performance management. The following are a few protocols:- HTTPS, HTTP, FTP, Web Services, etc.

) Define the benefits of testing applications based on Windows?

Ans. It provides excellent functionality and better Integration.

) Define the key factors that need to be considered during performance testing?

Ans. The following are various factors or elements that need consideration while doing a performance test.

• Difference between the previous test result values.
• Test Failure Reasons.
• Duration of the test.
• To document the test results for better analysis.
• The resulting document should include- the number of users, the purpose of testing, response time, throughput, error detected, suggestions, etc.
• To check graphs and charts of previous reports.

) Distinguish between Performance Engineering and Performance Testing?

Ans. Performance testing is the process of identifying problems that interrupt the application testing performance. But the term Performance Engineering refers to improving the application performance by monitoring the performance testing measurements. It also includes important changes in architecture, implementation, resources, etc.

) Do application end-users can run performance testing?

Ans. No, end-users cannot run the performance testing like professional testers. They can only detect the issues while using the software in real time. But the end-user can participate in performance testing with assistance through the User Acceptance Testing stage.

) What key factors to consider while testing a Web-based application?

Ans. The following are the key factors to consider in the web-based test:-

• Proper Response Time
• GUI
• Page text
• Broken links on the web

) Name the various tools available for Web testing?

Ans. JMeter and Selenium are the most important tools available for web testing.

) List out the different types of bugs in Web Testing?

Ans. The Web Testing bugs include:-

• Usability Bugs
• Form Validation Bugs
• GUI related issues
• Functionality related bugs
• Problems in the navigation of the application
• Issues with cross-browser adaptability

) Define JMeter?

Ans. JMeter is a helpful Java tool to execute performance load testing. It is helpful to analyze and measure the performance level of various services and products related to web applications. The latest version of Apache JMeter is 5.5. Further, we can use JMeter with Jenkins by integrating JMeter tests within the pipeline.

) What is meant by Neo load?

Ans. Neo load is a kind of load testing tool using which we can measure the web/mobile application’s performance. This tool is available in two languages- French and English. Through this, developers will get programmatic solutions that help optimize the application performance before it moves to production. 

Conclusion :

All the above are the most frequently asked Performance testing Interview questions by the top companies. These are not the mandatory questions to be asked in your interview, but they are more likely to be asked and learning them may help you clear your Performance testing interview. These questions have been provided to help you understand the pattern and how to answer them properly. A better approach and how to respond to questions can help you clear your interview. You could go through these questions and advance your career.

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