Topic: Performance testing and LoadRunner

Why performance testing?

1. Are you sure that users will have a positive experience on go-live day?
2. Does the application respond quickly enough for the intended users?
3. Will the application handle the expected user load and beyond?
4. Will the application handle the number of transactions required by your business?
5. Will the application responds with fast response time?

It is very difficult to run the performance tests manually because it may need a large number of resources and client machines and still it will be difficult to synchronize users and collect and analyze results. And to add to these think of the effort you will have to put to re-run these tests.

The solution here lies in using Mercury LoadRunner tool for running the performance tests.

Mercury LoadRunner Testing Tool

Mercury LoadRunner is a load testing product that determines application scalability, behavior, and performance. It emulates thousands of virtual users and identifies and isolates performance bottlenecks across and within each tier.

LoadRunner components

LoadRunner contains the following components

Virtual User Generator (VuGen): Records Vuser scripts that emulate the steps of real users using the application. In testing environment the LoadRunner replaces human users with virtual users (Vusers). Vusers create load by emulating actions of typical users.

VuGen works on record and playback principle. You have to walk through a business process or test process on your application which is recorded by VuGen into scripts. Then you can run these scripts n times simulating the test case of n users performs that particular business process simultaneously.

Controller: The administrative center for creating, executing and monitoring Scenarios. It provides you the tools to create the scenarios. Or in other words you can set attributes of your scenarios here (like think time). For example you may want 10 users log into a system simultaneously, you can use rendezvous event.

Analysis: Uses the Load Test results to create graphs and reports. This is to identify bottlenecks and performance issues or any other failures in your system’s performance and then pinpoint the source of these failures.

Understanding Load Runner Terminology

Scenarios - A scenario identifies the scripts to execute, the number of Vusers, goals of the test and the conditions under which to run the tests.

Vusers - Vusers emulate the actions of human users working with your application. A scenario can contain tens, hundreds, or even thousands of Vusers.

Vuser Scripts - The actions that a Vuser performs during the scenario are described in a Vuser script.

Transactions - To measure the performance of the server, you define transactions. A transaction represents end-user business processes that you are interested in measuring.

Load Generators – They are dedicated machines which are used to run the Vusers that generate load on the application under test.



The LoadRunner Solution

• Overcomes resource limitations by creating Vusers. There is no limitation on the number of Vusers created ( except if you do not have the license)
• Vusers are run on fewer machines than required for manual testing. One Load Generated is good enough to create 1000 Vusers.
• It provides controller to manage Vusers during the test.
• Allows repeatable tests with scripted actions.
• Provides meaningful results.