Introduction to Load Runner

Introduction to Load Runner

HP Load Runner is an automated performance and test automation product from Hewlett-Packard for examining system behaviour and performance, while generating actual load. HP acquired Load Runner as part of its acquisition of Mercury Interactive in November 2006.
Load Runner can emulate hundreds or thousands of concurrent users to put the application through the rigors of real-life user loads, The results can then be analysed in detail, to explore the reasons for particular behavior.

Load Runner supports various application protocols; Flex AMF, Citrix ICA, Remote Desktop Protocol (RDP), ERP/CRM (e.g. SAP, Oracle eBusiness, Siebel and PeopleSoft), Databases, Mail Clients, Web Services, and AJAX TruClient (with V.11.0).

Load Runner Components:

1.    Virtual User Generator (VUGen):

Virtual User Generator (VuGen) –records Vuser scripts that emulate the steps of real users using the application.

2.    Controller:

The Controller is an administrative centre for creating, maintaining, and executing Scenarios. The Controller assigns Vusers and load generators to Scenarios, starts and stops load tests, and performs other administrative tasks.

3.    Load Generators : 

Load generators (also known as hosts) are used to run the Vusers that generate load on the application under test.

4.    Analysis: 

LR Analysis uses the load test results to create graphs and reports that are used to correlate system information, identify bottlenecks, and performance issues.

Advantages of Load Runner

1.    Uses ANSI C as the default programming language1 and other languages like Java and VB.
2.    Excellent monitoring and analysis interface where you can see reports in easy to understand coloured charts and graphics.
3.    Supports most of the protocols.
4.    Makes correlation much easier.
5.    Nice GUI generated script through a one click recording; of course you would need to modify the script according to your needs.
6.    Excellent tutorials, exhaustive documentation and active tool support from HP.
7.    The protocol adviser is an excellent feature, which suggests the type of protocol to be used.


What all we can test using LR?

Load Runner supports various application protocols shown in screen shot below. 



Why Load Runner?

Load Runner is most popular load testing tool from HP which is used for load test & Stress testing to test performance of the application with respect to no. of users, response time & throughput. It is compatible with several protocols and also provides excellent analysis and reporting features.

Load Runner Architecture

    


Load Runner Workflow

 

Step 1: Plan the Load Test

1.    Identify Business Critical Scenarios.
2.    Estimate User Load. Performance Testing requirements will give an idea of users load or the number of users using the product.
3.    Finalize the scenarios to be automated

Step 2: Record the Scenarios in VuGen

VuGen records Vuser Scripts that emulate the steps of real users using the application. VuGen records sessions on Windows platforms only. However, a recorded Vuser script can run on both Windows and UNIX platform.

Step 3: Playback the Scenarios in VuGen

For sanity purpose and to check if script executes correctly, replay the script. The script should be replayed successfully with no errors. In case of errors, debug the script to find out root cause and regenerate a new script.

Step 4: Enhance the script with parameterization and correlation

To generate a realistic scenario, always handle dynamic data, User inputs should not be hard coded, they must be parameterized. In case a application has dynamic data from server, they must be co-related.

Step 5: Run the script for multiple users

After ensuring your script works fine and is ready for testing, try running the script for multiple users according to scenarios defined. The scenarios specific can be defined in the “LR Controller”. We can manage; schedule various scenarios using “LR Controller”.

Step 6: Analyse Results and Prepare Reports

Analyse the results in “LR Analyser” and view the metrics to decide system performance under load inputs.
Prepare reports collecting all the useful data derived from “LR Analyser” and summarize your observations and results.

Disadvantages of Load Runner

1)    The only disadvantage I can think is the prohibitive cost associated with the tool but that can also be compensated in the long run when you start getting a good ROI from the tool.
2)    VuGen records sessions on Windows platforms only. But it can replay on Unix and Linux Platforms once script is recorded.