Load runner

Load runner

HP Mercury’s LoadRunner is a performance testing and load testing tool by for evaluating the system performance while generating simulated load. By using LoadRunner, we can emulate hundreds and thousands of concurrent users to the application or software product; so that it can be tested under a heavy real life user loads.

LoadRunner consists of three components:

• Virtual User Generator called as VuGen
• Controller
• Analysis

1. VuGen: Virtual User Generator is a place to record and write automated scripts. It allows a software test professional to record/modify/write scripts for the application under test (AUT). Basically, a performance tester record the script and then play back and make modifications to the script if required. A tester may need to do correlation or Parameterization etc. I’ll explain these in some other posts.
2. Controller: After creating the script in VuGen, Controller is used to run the script. It controls load generators and scenarios associated with them. Normally, LoadRunner use various machines called as Load Generators to generate load. Each test  run is configured with a scenario that describe:

• What all scripts will run
• When they will run
• How many virtual users will run
• Which Load Generators will be used for each script

Performance tester connects each script in the scenario to the name of machine that is going to act as a Load Generator. During a load test, monitors are used by LoadRunner to monitor the performance of components under load. Overall, we can say that controller organizes, drives, manages, and monitors the load test.
3. Analysis: Once the run is completed after  setting the scenario, the result of the scenario is viewed using Analysis tool. This component creates the graphs for the performance tester to view. Graphs can also be merged to get a good analysis of the performance. Reports including all the necessary graphs can be saved in various formats like HTML and Microsoft Word format etc.