LoadRunner 
  • LoadRunner is a Performance Testing tool that was prepared by Mercury in 1999. 
  • LoadRunner was later developed by HPE in 2006. In 2016, 
  • LoadRunner was developed by MicroFocus.
  • LoadRunner supports various development tools, technologies, and communication protocols. 
  • It is the only tool on the market that supports such a large number of protocols for Performance Testing.
  •  Performance Test Results produced by LoadRunner software are used as a benchmark against other tools.

Introduction to LoadRunner



Why LoadRunner?
  • LoadRunner is not only an innovative tool in Performance Testing but also a market leader. 
  • In a recent assessment, it had about 85% market share in the Performance Testing industry.
  • Broadly, LoadRunner tool supports RIA (Rich Internet Applications), Web 2.0 (HTTP/HTML, Ajax, Flex and Silverlight etc.), Mobile, SAP, Oracle, MS SQL Server, Citrix, RTE, Mail, and above all, Windows Socket. 
  • No competitor tool in the market could offer such a wide variety of protocols vested in a single tool.
  • LoadRunner software is tightly integrated with other HP Tools like Unified Functional Test (QTP) & ALM (Application Lifecycle Management) which empowers you to perform your end-to-end Testing Processes.
  • LoadRunner works on the principle of simulating Virtual Users on the subject application. These Virtual Users also termed as VUsers, replicate client’s requests and expect a corresponding response to passing a transaction.
  • When a software system is deployed by an organization, it may encounter many scenarios that possibly result in performance latency. Several factors cause decelerating performance, 
A few examples may include:
• Increased number of records present in the database
• Increased number of simultaneous requests made to the system
• A larger number of users accessing the system at a time as compared to the past


LoadRunner Architecture

Suppose you are assigned to check the performance of Amazon.com for 5000 users
In a real-life situation, all these 5000 users will not be on the homepage but in a different section of the website. How can we simulate differently?

VUGen

VUGen or Virtual User Generator is an IDE (Integrated Development Environment) or a rich coding editor. VUGen is used to replicate System Under Load (SUL) behavior. VUGen provides a “recording” feature that records communication to and from the client and Server in the form of a coded script – also called VUser script.

So considering the above example, VUGen can record to simulate the following business 
processes:
1. Surfing the Products Page of Amazon.com
2. Checkout
3. Payment Processing
4. Checking MyAccount Page

Controller

Once a VUser script is finalized, the Controller is one of the main LoadRunner components that control the Load simulation by managing, 

For example:
• How many VUsers to simulate against each business process or VUser Group
• Behavior of VUsers (ramp up, ramp down, simultaneous or concurrent nature, etc.)
• Nature of Load scenario e.g. Real Life or Goal Oriented or verifying SLA
• Which injectors to use, how many VUsers against each injector
• Collate results periodically
• IP Spoofing
• Error reporting
• Transaction reporting etc

Agents Machine / Load Generators / Injectors

HP LoadRunner Controller is responsible for simulating thousands of VUsers – these VUsers consume hardware resources for example processor and memory – hence putting a limit on the machine that is simulating them. Besides, the Controller simulates these VUsers from the same machine (where the Controller resides) & hence the results may not be precise. To address this concern, all VUsers are spread across various machines, called Load Generators or Load Injectors.

As a general practice, the Controller resides on a different machine, and load is simulated from other machines. Depending upon the protocol of VUser scripts and machine specifications, several Load Injectors may be required for full simulation. 

For example, VUsers for an HTTP script will require 2-4MB per VUser for simulation, hence 4 machines with 4 GB RAM each will be required to simulate a load of 10,000 VUsers.

Analysis

Once Load scenarios have been executed, the role of the “Analysis” components of LoadRunner comes in.

During the execution, the Controller creates a dump of results in raw form & contains information like, which version of LoadRunner created these results dump and what were configurations.

All the errors and exceptions are logged in a Microsoft access database, named, output.mdb. The “Analysis” component reads this database file to perform various types of analysis and generates graphs.

These graphs show various trends to understand the reasoning behind errors and failure under load; thus help to figure out whether optimization is required in SUL, Server (e.g. JBoss, Oracle), or infrastructure.

Below is an example where bandwidth could be creating a bottleneck. Let’s say the Web server has 1GBPS capacity whereas the data traffic exceeds this capacity causing subsequent users to suffer. To determine system caters to such needs, the Performance Engineer needs to analyze application behavior with an abnormal load.

How to Do Performance Testing

Performance Testing Roadmap can be broadly divided into 5 steps:
• Planning for Load Test
• Create VUGen Scripts
• Scenario Creation
• Scenario Execution
• Results Analysis (followed by system tweaking)


Download the link for: LoadRunner
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