Performance Testing, LoadRunner Tips&Tricks

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Products: LoadRunner

LoadRunner is a load testing tool that allows load testing against various technologies (or protocols to be specified). The load testing is by done generating load of emulated real users in the form of scripts or in the LoadRunner terminology, Vusers. While load generating, monitoring is applied to the SUT (System Under Test) or servers and collected at the end of the load testing. This data, is then been analyzed to determine the next course of action (depending on the objective of the load test, i.e. benchmarking, SLA, stress testing, etc.) such as tuning, scaling, or defining a new SLA, etc.

If you like to know more on the sales talk (again), feel free to explore the HP Software website here.

LoadRunner have a couple of components that makes up the whole product, namely, the Vugen, Controller, Load Generator and Analysis. Take note that Diagnostics and SiteScope is a separate product by itself although it comes along with every LoadRunner CD. It would deserve more description than it will have here. The idea of LoadRunner is fairly simple, it is to generate load based on a described business process, emulated users in the form of ANSI C scripts.

The components described, facilitates the load testing in the following manner. Vugen generates scripts that emulate the real users through recording a described business process that real users would perform. The recording is somewhere like a network sniffer on the protocol described and will generate a basic script that describes the user actions. From here, modifications can be made to the scripts such as runtime settings, parameterization and correlation, and not limited to the two mentioned.

Once the scripts (Vusers) are ready, a scenario is created in the Controller. The scenario defines the number of Vusers (scripts) to generate, the duration of the scenario, the behavior of the Vusers, and the resources (servers) that the tester would like to monitor. It also defines the Load Generators to use and any additional components such as IP Spoofing or Diagnostics module. When the scenario is done, all the tester needs to do is to run the scenario and wait for the results to be collected at the end of the test. More information on how the monitors in LoadRunner work can be found here.

When the scenario is started, the scripts are sent by the Controller to the Load Generator and the Load Generator wills generate the defined assigned amount of load to the SUT. As the name implies, Load Generator generates load and Controller controls the scenario execution.

After the load testing data have been collected. It will be save in a results folder and been port over to Analysis for performing analysis of the results. Analysis is a powerful graphical tool to look at correlations between load and system resource performance (and many more depending on what you are entitled to monitor). However, take note that having a powerful tool does not give the tester wings to fly. The tester will still need the relevant experiences and knowledge to determine bottlenecks in the system. (Usually companies charge this as consultancy).

The above is described in more detail in a popular site describing LoadRunner architecture. If you are interested in the details, please feel free to explore here.

LoadRunner is tied to one license which entitles to the (1) number of Vusers (concurrent users) that are being generated, the (2) protocol that the Controller is able to run and the (3) available monitors that the organization can utilized. This information can be found in the LoadRunner License Information. The restriction of the license only applies to the Controller. Therefore, Vugen and Analysis is still functional even if the license is not applied or expired.

Some pitfalls; There are always questions on client activities been recorded in LoadRunner (Vugen). I believed it’s the association of Functional Testing with the idea of Performance/Load Testing. Take note that they are two different things. Performance/Load Testing involves a lot of knowledge on architecture, applications, etc. It is not as simple in testing GUI on the front end and ensuring that the output is correct.

LoadRunner is designed to load test a designated server and not client. Whatever activities performed by the client is not recorded. This had been a popular question posted frequently on the web and I feel that association should be corrected. For this, I’ve also written an article on it. Click here if you like to know more details.

Installation; for LoadRunner to function properly, it’s advisable to install with the default administrator rights. Installation or functionality problems are usually caused by insufficient privileges to the installed machine, clone images or anti-virus software.

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1 Responses to “Products: LoadRunner”

  1. # Anonymous Anonymous

    Hello All,

    i am using .NET client/Server application. Recording the scripts using win32 option.
    But i am facing problem once i parameterize the value, i want to cross check the values.
    Can anybody tell me how to cross check the results once the replay is done.  

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