Monday 3 June 2013

Load Runner Interview Questions ans Answers

Load Testing Questions and Answers

1. What is load testing?

Answer: Load testing checks if the application can handle lots of users and tasks at once, like during busy times. It helps to see if the app can handle heavy usage without slowing down or crashing.

2. What is performance testing?

Answer: Performance testing checks how well a computer, network, or software works. It measures things like how fast it responds or how many tasks it can do at once.

3. Did you use LoadRunner? Which version are you using?

Answer: Yes, we are using LoadRunner version LRE 2022.

4. Explain the load testing process.

  1. Know your testing environment.
  2. Set performance goals.
  3. Plan and design tests.
  4. Configure the test environment.
  5. Implement test design.
  6. Run the tests.
  7. Analyze and retest.

5. When do you do load and performance testing?

Answer: Load testing is done after QA testing. It's important for checking how the system performs under heavy use, unlike single-user testing which focuses on individual features.

6. What are the components of LoadRunner?

Answer: The components are Virtual User Generator, Controller, Agent process, LoadRunner Analysis and Monitoring, and LoadRunner Books Online.

7. What component of LoadRunner would you use to record a script?

Answer: You use the Virtual User Generator (VuGen) to record a script.

8. What component of LoadRunner would you use to play back the script in multi-user mode?

Answer: The Controller component is used to play back the script in multi-user mode during a scenario run.

9. What is a rendezvous point?

Answer: Rendezvous points make Vusers wait during testing so they can perform tasks at the same time, mimicking heavy user load on the server.

10. What is a scenario?

Answer: A scenario defines the events during testing, like how many users to simulate and what actions they'll take.

11. Explain the recording mode for a web Vuser script.

Answer: VuGen records user actions on a client application, monitoring communication with the server and creating function calls in a Vuser script.

12. Why do you create parameters?

Answer: Parameters vary input to the server, simulating real users. They help simulate different user behaviors.

13. What is correlation? Explain the difference between automatic correlation and manual correlation.

Answer: Correlation avoids errors from duplicate data. Automatic correlation sets rules to replace values, while manual correlation scans and replaces specific values.

14. How do you find out where correlation is required?

Answer: You can scan for correlations or compare scripts to find differences in values that need correlating.

15. Where do you set automatic correlation options?

Answer: In LoadRunner, you can set automatic correlation options in recording settings or by scanning for correlations.

16. What is a function to capture dynamic values in the web Vuser script?

Answer: The Web_reg_save_param function captures dynamic data in a web Vuser script.

17. When do you disable logging in Virtual User Generator, and when do you choose standard and extended logs?

Answer: Logging is disabled once the script is functional. Standard logs are used for debugging, and extended logs provide more detailed information.

18. How do you debug a LoadRunner script?

Answer: You can debug using "Run Step by Step" or breakpoints in VuGen. Debug information is written to the output window.

19. How do you write user-defined functions in LR? Give a few functions you wrote in your previous projects.

Answer: You create an external library and assign user-defined functions as parameters. Examples include GetVersion and GetCurrentTime.

20. What are the changes you can make in run-time settings?

Answer: You can change pacing, logging, think time, and general settings like Vuser processes.

21.Where do you set Iteration for Vuser testing?

Answer: Iterations are set in the Run Time Settings of VuGen, under the Pacing tab.

22.How do you perform functional testing under load?

Answer: By running multiple Vusers concurrently, you can test functionality under load and see how well the server handles it.

23.What is Ramp up?

How do you set this?

Answer: Ramp up gradually increases Vusers/load on the server. You can set it in the Scenario Scheduling Options.

24.What is the advantage of running the Vuser as a thread?

Answer: Running Vusers as threads allows more Vusers per generator, saving memory and enabling more concurrent users.

25.If you want to stop the execution of your script on error, how do you do that?

Answer: Use the lr_abort function to stop script execution on error, and uncheck "Continue on error" in Run -Time Settings.

26.What is the relationship between Response Time and Throughput?

Answer: Throughput indicates data received per second, and as it scales with Vusers, response time may increase if the server's bandwidth is insufficient.

27.Explain the configuration of your systems.

Answer: System configuration includes hardware, software, and settings. It should match the overall system configuration for accurate load testing.

28.How do you identify performance bottlenecks?

Answer: Performance monitors help find bottlenecks by measuring response time, throughput, and network delays.

29.If the web server, database, and Network are all fine, where could the problem be?

Answer: The problem could be in the system itself, application server, or code.

30.How did you find web server-related issues?

Answer: Web resource monitors analyze web server performance, measuring throughput, and HTTP responses.

31.How did you find database-related issues?

Answer: By running database monitors and analyzing data resource graphs, you can find database performance issues.

32.Explain all the web recording options.

Answer: Web recording options in LoadRunner capture user actions, HTTP/HTTPS data, and web-based interactions.

33.What is the difference between Overlay graph and Correlate graph?

Answer: Overlay graph combines two graphs with a shared x-axis, while Correlate graph plots one graph's y-axis against another's x-axis.

34.How did you plan the Load?

What are the Criteria?

Answer: Load test planning is based on Task Distribution Diagram and Transaction Profile to determine user numbers and transaction priorities.

35.What does vuser_init action contain?

Answer: The vuser_init action includes procedures for logging into a server.

36.What does vuser_end action contain?

Answer: The vuser_end section contains log-off procedures.

37.What is think time?

How do you change the threshold?

Answer: Think time is user wait time between actions. You can change the threshold in VuGen's Recording options.

38.What is the difference between standard log and extended log?

Answer: Standard log records basic script functions, while extended log includes more detailed debugging information.

39.Explain the following functions:

Answer: - `lr_debug_message`: Sends a debug message to the output log. - `lr_output_message`: Sends notifications to the Controller Output window and Vuser log file. - `lr_error_message`: Sends an error message to the LoadRunner Output window. - `lrd_stmt`: Associates a string with a cursor for SQL statements. - `lrd_fetch`: Fetches the next row from a result set.

40.Throughput - If the throughput scales upward as time progresses and the number of Vusers increase, this indicates that the bandwidth is sufficient.

Answer: If throughput increases with Vusers, it means bandwidth is enough.

41.Types of Goals in Goal-Oriented Scenario

Answer: LoadRunner provides goals like concurrent Vusers, hits per second, transactions per second, pages per minute, and desired response time.

42.Analysis Scenario (Bottlenecks)

Answer: Bottlenecks can be seen when response time sharply increases with more Vusers, indicating a server overload.

43.What is correlation?

Explain the difference between automatic correlation and manual correlation?

Answer: Correlation replaces unique data in scripts. Automatic correlation uses rules, while manual correlation scans and replaces values.

44.Where do you set automatic correlation options?

Answer: Automatic correlation settings are in LoadRunner's recording options and correlation tab.

45.What is a function to capture dynamic values in the web Vuser script?

Answer: The function is `Web_reg_save_param()` which captures dynamic data in a web Vuser script.

46. What is the purpose of pacing in load testing?

Answer: Pacing in load testing controls the speed at which Vusers or transactions are executed. It helps simulate real-world scenarios where users don't perform actions instantly.

47.How do you determine the appropriate load levels for testing?

Answer: The appropriate load levels are determined based on the expected usage patterns and peak times of the application. It involves analyzing historical data, user behavior, and business requirements.

48.What is the difference between stress testing and load testing?

Answer: Stress testing evaluates how the system performs under extreme conditions beyond its normal capacity, while load testing assesses the system's behavior under typical and peak loads.

49.Explain the concept of parameterization in load testing.

Answer: Parameterization allows testers to vary input data during each test iteration, making scripts more realistic. It involves replacing hard-coded values with parameters that can be randomized or derived from external sources.

50.How do you analyze test results in LoadRunner?

Answer: Test results in LoadRunner can be analyzed using various graphs and reports generated during test execution. Key performance indicators such as response time, throughput, and error rates are examined to identify performance bottlenecks and areas for improvement.