Introduction of LoadRunner

LoadRunner is an industry-leading performance and load testing product by Hewlett-Packard (since it acquired Mercury Interactive in November 2006) for examining system behavior and performance, while generating actual load.

LoadRunner can emulate hundreds or thousands of concurrent users to put the application through the rigors of real-life user loads, while collecting information from key infrastructure components (Web servers, database servers etc). The results can then be analysed in detail, to explore the reasons for particular behaviour.

Consider the client-side application for an automated teller machine (ATM). Although each client is connected to a server, in total there may be hundreds of ATMs open to the public. There may be some peak times — such as 10 a.m. Monday, the start of the work week — during which the load is much higher than normal. In order to test such situations, it is not practical to have a testbed of hundreds of ATMs. So, given an ATM simulator and a computer system with LoadRunner, one can simulate a large number of users accessing the server simultaneously. Once activities have been defined, they are repeatable. After debugging a problem in the application, managers can check whether the problem persists by reproducing the same situation, with the same type of user interaction. Modern client/server architectures are complex. While they provide an unprecedented degree of power and flexibility, these systems are difficult to test. Whereas single-user testing focuses primarily on functionality and the user interface of a single application, client/server testing focuses on performance and reliability of an entire client/server system.

For example, a typical client/server testing scenario might depict 200 users that login simultaneously to a system on Monday morning: What is the response time of the system? Does the system crash? To be able to answer these questions– and more–a complete client/server performance testing solution must

• test a system that combines a variety of software applications and hardware platforms

• determine the suitability of a server for any given application

• test the server before the necessary client software has been developed

• emulate an environment where multiple clients interact with a single server application

• test a client/server system under the load of tens, hundreds, or even thousands of potential
users

Load Runner is divided up into 3 smaller applications:

The Virtual User Generator allows us to determine what actions we would like our Vusers, or virtual users, to perform within the application. We create scripts that generate a series of actions, such as logging on, navigating through the application, and exiting the program.

The Controller takes the scripts that we have made and runs them through a schedule that we set up. We tell the Controller how many Vusers to activate, when to activate them, and how to group the Vusers and keep track of them.

The Results and Analysis program gives us all the results of the load test in various forms. It allows us to see summaries of data, as well as the details of the load test for pinpointing problems or bottlenecks.