LoadRunner Interview Questions

Loadrunner is a software testing tool developed by Micro Focus that is used to test applications for measuring system behavior, and performance under load. Acquired by HP in November 2006, Loadrunner is available on Windows and Linux. A proprietary tool, Loadrunner simulates thousands of users concurrently using application software, recording and analyzing some of the key components of the applications.

Some of the key components of the LoadRunner are,

Load Generator - It is used to generate the load against the application by running the script.

VuGen - It is used for generating and editing scripts.

Controller - It is used to control, launch, and sequence the instance of a Load Generator.

Agent Process - It is used to manage the connection between the Controller and Load Generator instances.

Analysis - It assembles the logs from different load generators and formats the reports for visualization of results and monitoring data.

The agent in the LoadRunner helps the controller and the load generator to communicate with each other. When running a scenario, the controller instructs the remote agent dispatcher to launch the LoadRunner agent. Then the agent receives instructions from the Controller to run, pause, stop or initialize the Vusers. The agent also relays data on the status of the Vusers back to the controller.

VuGen is the first component that you interact with when starting the performance testing using HP LoadRunner. The two main features of the VUGen are the VUScripts and Actions.

VUScripts are used to simulate a real-like virtual user. Actions is a set of user transactions performed under load to achieve a defined task.

With VUGen, you can enable a variety of protocols. Each protocol is suited to a specific load testing environment or topology. You can run different tests on your application using protocol-specific Vuser scripts.

Some of the protocols that you can run with LoadRunner are .NET, C Vuser, Flex, FTP, Java over HTTP, IMAP, LDAP, MAPI, HTTP/HTML, and more.

The lr_abort function is used to exit the action selection in the vugen if any error occurs. It instructs the Vuser to stop executing the action section, execute the vuser_end section and end the execution.

Some of the alternatives to the LoadRunner are,

Apache JMeter - An open-source java application.

Locust - An open-source load testing python tool.

Gatling - An open-source load testing tool based on Netty, Akka, and Scala.

Loader.io - Cloud-based load testing service.

OctoPerf - A SaaS load testing solution.

Some other alternatives are Low Orbit Ion Cannon, Flood.io, Load Impact, blitz.io, and Fast DDoS Attack Cmd.

Correlation is used to define a relationship between two variables or entities. It is mainly used to take care of the data returned by the server.

There are two correlations available in LoadRunner. They are manual and automated correlation.

In manual correlation, you have to identify the dynamic value and capture it from the response of the previous post.

In automated correlation, you have to work with the existing rules.

Workload modeling is used to identify one or more workload profiles to be simulated against the tested application. It distributes the load across the identified transactions in a given time. This model can be designed by predictability, repeatability, and scalability. For designing a workload model, you need the number of concurrent users, total transactions to be achieved, scenarios and percentage of the total user for an action.