LoadRunner

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Mercury's LoadRunner is a performance and load testing product for examining system behavior and performance, whilst generating actual load. LoadRunner can emulate hundreds or thousands of concurrent users to put the application through the rigors of real-life user loads, whilst collecting information from key infrastructure components (web servers, database servers etc). The results can then be analysed in details, to explore the reasons for particular behaviour.

External links

[Homepage]

[LoadRunner Technical Information]

[LoadRunner UserGroup]

[LoadRunner Advanced User Group]

[Mercury Support Site]

Mercury LoadRunner is extremely useful when an application needs to be tested for multiple user access situations. Consider an ATM client-side application. Though each client is connected to a server, in total there may be hundreds of ATM machines open to the public. There may be some peak times, like Monday morning 10 AM, since it is the starting of Office hours after a weekend, there may a chance of users to use the ATMs in all its locations. In order to test such situations, it is not practical to have a number of ATM machines and to arrange that much number of people. So, if we have a ATM simulator and a computer system, with LoadRunner, we can emulate large number of user to access the server simultaneously. Thus a controlled monitoring can be possible.

Another advantage is that once activities have been defined, they are repeatable. After correcting a problem in the application, managers can check whether the same problem exists by reproducing the same situation, with the same type of user interaction.

Working in Loadrunner involves using three different tools which are part of Loadrunner. They are Virtual User Generator (VuGen), Controller and Analysis.

VuGen The VuGen allows a user to do the scripting of the application to undergo the test and enables the performance tester to playback and make modifications to the script as needed. The modifications involves activities like Parameterization(Providing data for runtime), Correlation and Error handling.

Controller Once a script is prepared in Vugen, it is run via the Controller. Each run is called as a scenario with some preset settings. Loadrunner provides the usage of various machines to act as LoadGenerators, i.e., to run a test of 100 users, we can use three or more machines with Loadgenerator installed in them. The tester will then provide the script and the name of the machine which is going to act as a load generator along with the number of users who are going to run from that machine. LoadRunner uses Monitors to monitor the performance of individual components. But each monitor is to be purchased seperately from Mercury. Some monitors include Oracle Monitors, WebSphere Monitors, etc... Once a scenario is set and the run is completed, the result of the scenario can be viewed via the Analysis tool

Analysis This tool takes the completed scenario result and prepares the necessary graphs for the tester to view. The tester can then make needed adjustments to the graph and then can prepare a Loadrunner report. The LR report is mostly in Word format with all the necessary graphs in them. Also, graphs can be merged to get a good picture of the performance.

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