Performance Testing Interview Questions


1. What are the performance testing process you follow in your organization?
Answer: In my current organization, we have different teams handling different applications. When an application needs performance testing, corresponding project manager communicates with the performance team manager and our manager then allocate resources. We, the performance tester then has meetings with project team to gather performance testing requirements.
Once we have collected all of the requirements and have clear understanding about the performance testing business scenarios/test cases, we prepare our performance test plan and provide a walkthrough on the plan to project teams.
We then script the test cases and then execute multiple performance tests to make sure that application is satisfying all of the performance criteria. If there is any performance issue, we let the application teams to resolve the issue. Once the performance issue is resolved we execute further performance tests to validate the performance.
Once the executions are done, we prepare a report on the performance test executions and provide a walkthrough to different teams.
We perform all of the above activities according to performance test plan and according to specific deadlines.

2. What are the components of LoadRunner?
Answer: The components of LoadRunner are The Virtual User Generator, Controller, and the Agent LoadRunner Analysis tool.
3. Why do you use the virtual user generator?
Answer: We use virtual user generator to create automated performance testing scripts.
4. Why do you use Controller?
Answer: We use Controller to create load profile and to schedule and execute performance tests.
5. Why do you use Analysis tool?
Answer: We use Analysis tool to analyze the performance test results and to generate reports.
6. When and why do you do load and performance Testing?
Answer: We perform load testing once we are done with interface (GUI) testing. Modern system architectures are large and complex. Whereas single user testing primarily on functionality and user interface of a system component, Performance testing focuses on performance and reliability of an entire system. For example, a typical application-testing scenario might depict x (for example 1000) users logging in simultaneously to a system. This gives rise to issues such as what is the response time of the system, does it crash, can it hold so many hundreds and thousands of users, etc. This is when we set do load and performance testing.
7. What is a rendezvous point?
Answer: You insert rendezvous points into Vuser scripts to emulate heavy user load on the server. Rendezvous points instruct Vusers to wait during test execution for multiple Vusers to arrive at a certain point, in order that they may simultaneously perform a task. For example, to emulate peak load on the bank server, you can insert a rendezvous point instructing 100 Vusers to deposit cash into their accounts at the same time.


8. Why do you create parameters?
Answer: Parameters are like script variables. They are used to vary input to the server and to emulate real users. Different sets of data are sent to the server each time the script is run. By using parameters, we do better simulate the usage model for more accurate testing from the Controller; one script can emulate many different users on the system.
9. What is correlation? Explain the difference between automatic correlation and manual correlation?
Answer: Correlation is a process where we capture a dynamic value from a previous request in the script and use it in the subsequent request or requests.
Automatic correlation is where we set some rules for correlation and Virtual user Generators(VuGen) prepares a list of values to be correlated. We can correlate those values easily then by simply clicking on them. Sometimes it will bring unnecessary data for correlation.
In manual correlation, after recording the script we manually scan for dynamic values and then provide left and right boundaries manually to loadRunner function(web_reg_save_param or web_reg_save_param_ex) to capture the value. Then we use this value for the subsequent requests.
10. Name some Server Performance Monitoring Tools.
Answer: HP SiteScope, HP Performance Manager.