LoadRunner formerly a product from Mercury (now acquired by HP) is a load testing tool that facilitates load testing against application thus determining the behavior of the application (server and network) when under normal load, stress or prolonged testing depending on the objective of the load test. If you are new to this product, it will be worthwhile to spare some time to read through this post.

How does it work is fairly simple (avoiding the technical complexity this tool can posed). Scripts are generated using protocol-level capturing tool (Vugen). This scripts, also known as Vusers, are placed in a Scenario in the Controller and are generated to emulate the real users accessing the application. While load testing, monitoring data is collected from the servers or SUT (System Under Test) and are collected at the end of the test. This data, is then been analyzed for bottlenecks and behavior 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 about the product from a vendor perspective, explore the HP Software here.

When the scenario is started, the scripts are sent by the Controller to the Load Generator and the Load Generator will generate the defined assigned amount of load to the SUT. As the name implies, Load Generator generates load and Controller controls the scenario execution. Throughout the load test, data is been consistently collected, such as running users, throughput, system resources and can be configured to receive more than those described here.

When the load test completes, the load generators will send back the data collected and stored in a results folder in the Controller. This data is then being used by Analysis to perform analyzing work. 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).

If you like to have details of the LoadRunner architecture, you can explore the site by Wilsonmar for such information while I try to simplify it for the convenience of the beginners.

LoadRunner is tied to one license which entitles to (1) the number of Vusers (concurrent users) that can be generated, (2) the protocol that the Controller is able to execute and (3) the 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 will still be functional even if the license is not applied or expired.