A complete understanding of the software performance is only possible with the help of a qualified Performance tester. So, many companies provide a number of opportunities to select the right candidate for the role of a performance tester. To grab the opportunities, knowledge related to Performance testing is essential. To assist you in clearing your interview, we have gathered and come up with the most frequently asked Performance testing interview questions. So Let's get started with the Performance testing interview questions.
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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.
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.
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.
The following are some common performance issues that users face:
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:
The following are a few common performance bottlenecks:
The performance tests are based on the following parameters:
Factors to remember when selecting Performance Testing Tools 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.
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.
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.
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.
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.
Following are some of the advantages of LoadRunner:
The automated performance testing phases include the following:
The activities associated with performance testing are:
Following are some of the common mistakes in performance testing:
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.
Performance tuning is improving system performance. Usually, in computer systems, the motivation of activity is referred to as a performance issue. It may be real or expected, and most systems will meet an increased load with a certain degree of diminishing efficiency.
Performance Tuning can be divided into two types:
Hardware Tuning: Hardware tuning involves improving, adding or replacing the tested system hardware components and making framework level changes to improve system performance.
Software Tuning: Software tuning involves Identifying software-related bottlenecks through profiling code, database, etc. Fine-tuning or editing software to correct bottlenecks is referred to as software tuning.
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 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.
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.
A number of disadvantages of manual load tests have led to the adoption of automated load tests. Some reasons are as follows:
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.
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.
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.
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.
Each step of the script is validated with the content over the returned page. A content check makes it possible to check whether particular content is present on the webpage or not. In LoadRunner, there are two kinds of content checks:
Text Check: It verifies if there is any text or string on the webpage.
Image Check: The purpose of an image Check is to verify an image of a webpage.
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.
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.
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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