August 31, 2018

What is Load Testing – A Quick Tutorial

Load testing helps to determine the behavior of an application when large numbers of users access the application simultaneously. It is a type of performance testing which identifies the maximum operating capacity of an application.  This helps to know whether the existing infrastructure is capable to run the application or not. Load testing is conducted to determine the number of concurrent users that an application can support without deterioration in performance. This testing is usually performed for client/server and web-based application.

Outcomes of Load Testing:

Load testing helps to identify the following parameters:

  • The response time of each transaction of the application
  • Performance under different load conditions of system components
  • Performance under different load conditions of database components
  • Network delay between the client request and server response
  • Issues in software design
  • Limitations due to hardware like CPU maximization, network bottleneck, memory limitation, etc.
  • Issues in software configuration such as web server, application server, database server etc.

Load Testing

Load Testing vs. Stress Testing

Load testing and Stress testing are both subsets of the performance testing. Performance testing is conducted to find out the response time, speed, scalability and the resource utilization of the software and infrastructure.  While load testing tests the system under peak traffic conditions, stress testing is used to test the system behavior beyond peak conditions and the response of the system when it is returning to normal load conditions.

Advantages of Load Testing

There are several advantages of load testing as listed below:

Improved scalability

Load testing helps to identify the number of users the application can support. This helps in determining the need for additional infrastructure in case there is a demand for scaling the application.

Reduction in system downtime

Load testing gives a better picture of an application’s limitation when it goes live.  The solution to high volume traffic problem can be made beforehand which reduces the system downtime considerably.

Reduction in cost due to failures

The failures during production can cause significant cost due to unavailability of application or any other such problem. With load testing, the defects can be prevented before they arise reducing cost implications of failure.

Improved customer satisfaction

With lesser number of system downtimes and ability to serve to a large number of users, the overall customer satisfaction with the application increases which causes users to revisit the site more often.

Load Testing Examples:

Some basic examples of load testing are:

  • Testing a printer by transferring a large number of documents for printing
  • Testing a mail server with thousands of concurrent users
  • Testing a word processor by making a change in the large volume of data

Most Popular Load Testing Tools:


It is a 100% cloud-based load testing tool that offers on-demand load testing. A user can perform real browser testing along with testing on 40+ devices with support for multiple browsers.  It also allows multi-location load testing with the capability to simulate user behavior for web apps, portal logins and web transactions in a real browser.  It generates a sequence of HTTP GET/ POST request to test web servers and Web APIs.


This load testing platform is well equipped for Agile and DevOps development environment. It offers automated test design along with maintenance and analysis to enable continuous delivery. This tool provides integration with other tools in the testing ecosystem such as Jenkin for CI servers, Selenium for functional testing and Dynatrace for APM. It also supports shared test scripts and reports that are formulated in real-time and post-test completion.


It is a highly flexible tool that supports multiple integrations and its scripting allows users to run complex test scenarios.  WebLOAD supports many technologies, network protocols, enterprise applications and operating systems.

Load Runner

This is a Load test tool by HP which is used to test the application by generating load. It tests the application by creating virtual users to simulate normal and peak network traffic conditions. The tool simulates a production environment and displays graphical results.

How to do Load Testing?

Load testing can also be performed without the help of any load testing tools.  The basic steps to do load testing for an application are listed below:

  • The first step involves creating a dedicated test environment for load testing
  • The next step includes determining the Load test scenarios
  • Then we determine the load testing transactions for the application that include:
    • Preparing test data for each transaction
    • Predicting the number of users accessing the application
    • Determining the connection speeds
    • Determining the different browsers and operating systems on the user’s end
    • Configuring web, application and DB servers
  • Execute the test scenario and monitor the results by collecting various metrics
  • Analyzing the results for making recommendations
  • Tuning the system and retesting it


Load testing is a critical part of the software testing process as it ensures that the software performs to render high user satisfaction. A successful load testing will help to release high-quality software.

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