Load Testing Tutorial (Definition, how to, Example)

Load Testing

Load testing is a type of non-functional software testing in which the execution of a software application is judged under a particular load. It controls how the software application works when a large number of people use it at the same time. Prior to deployment, load testing is done to detect performance bottlenecks and guarantee that software programs are stable and run smoothly.

This analysis typically determines: -

  • An application's maximum operational capacity

  • Examine whether the current infrastructure is capable of handling the application.

  • The app's viability in terms of peak user load is debatable.

The maximum number of concurrent users supported by an application, as well as its scalability, enables additional users to access it.

It's a type of non-functional testing. Load testing is widely used in Software Engineering for Client/Server and Web-based applications on both the Intranet and the Internet.

What is the purpose of load testing?

Load testing establishes trust in a system's reliability and performance.

Load testing recognizes system bottlenecks under high-volume user stress circumstances before they take place in a production environment.

Load testing provides good protection against poor performance and can be used in conjunction with other performance management and monitoring tactics in a production setting.

Why Load Testing is required?

Load testing is required since some of the most popular websites have had significant downtime when they receive large amounts of traffic. At the time when marketing pulls in visitors, e-commerce websites invest extensively in advertising efforts, but not on Load Testing to ensure optimal system performance.

Consider the examples below.

Toysrus.com, a popular toy retailer, was unable to handle the increased traffic created by their advertising campaign, resulting in a loss of marketing costs as well as potential product sales.

During a festive deal, a website for an airline was unable to accommodate 10,000+ customers. As a promotional offer, Encyclopedia Britannica made free access to their online database available. For weeks, they couldn't keep up with the influx of traffic.

When a website receives a lot of traffic, it takes longer for it to load.

Facts −

  • After an 8-second delay in loading a page, most people click away.

  • 4.4 billion dollars are lost each year due to inadequate performance.

Objectives of Load Testing

Before releasing the application to the market or into production, load testing identifies the following issues −

  • Each transaction's response time

  • System component performance under varying loads

  • Database component performance under various loads

  • Between the client and the server, there is a network delay.

  • Issues with software design

  • Web servers, application servers, database servers, and other server configuration difficulties.

  • Issues with hardware restrictions such as CPU maximizing, memory constraints, network bottlenecks, and so on.

  • Load testing will indicate if the system needs to be fine-tuned or if hardware and software modifications are needed to increase performance.

Load Testing Prerequisites

  • The most important statistic for load testing is response time. You must first identify - before you begin load testing.

  • Is the reaction time now being measured and compared? - Quantitative analysis

  • Whether or not the response time is relevant to the business process -

  • Whether or not the response time is reasonable - realistic

  • Whether the response time can be met - Yes, it can be met.

  • Whether the response time may be measured using a tool or by using a stopwatch - it must be measurable.

Before you begin load testing, you must first create the following environment −

Hardware PlatformSoftware Configuration
  • Server Machines

  • Processors

  • Memory
  • Operating System
  • Disk Storage
  • Server Machines
  • Load Machines configuration

  • Network configuration

Load Testing Strategies

Load testing can be done in a variety of methods. A few load testing methodologies are listed below −

  • Manual Load Testing − This is one of the load testing methodologies, however, it does not give reproducible results, cannot offer measured levels of stress on an application, and is difficult to organize.

  • Load testing tools created in-house − An organization that recognizes the value of load testing may develop its own load testing technologies.

  • Load testing tools that are open source and free − There are various load testing programs that are open source and free. They may not be as complex as their paid equivalents, but they are the greatest option if you are on a budget.

  • Enterprise-level load testing software − They usually have a capture/playback feature. They are capable of supporting a wide variety of protocols. They have the ability to mimic a huge number of users.

Load Testing: A Step-by-Step Guide

The load testing procedure can be summarised as follows −

  • Establish a specialized load testing environment.

  • Figure out the following:

  • Scenarios for Load Testing

  • Determine an application's load testing transactions.

  • Prepare each transaction's data.

  • The number of users who will use the system must be estimated.

  • Find out how fast your connection is. Some users may have leased lines, while others may have dial-up access.

  • Determine the users' preferred browsers and operating systems.

  • All of the servers, such as web, application, and database servers, are configured.

  • Execution and monitoring of test scenarios. Various metrics are being collected.

  • Examine the outcomes. Please provide suggestions.

  • Re-test the system when it has been fine-tuned.

Load Testing Guidelines

  • Once the application is functionally stable, load testing should be scheduled.

  • In the data pool, a considerable amount of unique data should be available.

  • For each scenario or script, the number of users should be determined.

  • To save disc space, avoid creating extensive logs. I/O memory

  • Try to stay away from downloading photos from the site.

  • The consistency of reaction time overtime should be recorded, and the results should be compared to other test runs.

Guidelines for Best Practices

Some of the best techniques for load testing are described below −

  • Before commencing a load test, make sure the program is stable. Before the build is moved to the Load Test environment, the Functional Testing team should sign the application as functionally stable, and all major defects should be addressed and tested.

  • Check that the load test environment, including the number of servers, load balancers, server configurations, and firewalls, is a replica or close to the production environment

  • Before running a load test, double-check that the test data is unique and that all of the test data has been moved to the load environment.

  • Create test scenarios that closely resemble real-time user behavior in the production environment.

  • Generate the workload that is based on the manufactured user loads and business flows; if it's an old application, check if it's a new one, and converse to the business team regarding the business flows and user load.

  • Gather all relevant information, such as Response Time, Hits Per Second, Throughput, CPU, Memory, Network, and Running Vusers.

Load and Stress Testing: What's the Difference?

Load Testing − Testing under load discovers system bottlenecks under various workloads and evaluates how the system responds as the load is gradually increased

Load Testing −Stress Testing: Stress testing identifies a system's breaking point or the maximum point at which it will fail.

Distinction between Functional and Load Testing

The distinction between functional and load testing is as follows −

Functional Testing

  • Because we have defined correct stages and preconditions, the results of functional tests are easily predicted.

  • The outcomes of functional testing differ slightly.

  • Functional Testing will be performed on a regular basis.

  • The test data determines the outcome of functional tests.

Load Testing

  • Load test results are unpredictable.

  • The results of load tests differ dramatically.

  • The frequency with which load testing will be carried out will be modest.

  • The amount of users affects load testing.

Tools Used for Testing

LoadNinja − LoadNinja is changing the way people load tests. This cloud-based load testing tool enables teams to record and playback thorough load tests in real browsers at scale, without the need for complicated dynamic correlation. Teams have been able to enhance test coverage and reduce load testing time by more than 60%.

Eggplant − All of the top analysts, including Gartner and Forrester, have recognized Eggplant (now part of Keysight Technologies) as a leader in load testing solutions. Don't use yesterday's technologies to fight today's testing war.

LoadRunner − HP's Load Runner tool is used to test applications under regular and peak load circumstances. The load runner creates virtual users that simulate network activity to produce load. It generates graphical results while simulating real-time usage in a production context.

Load Testing Benefits and Drawbacks

The following are some of the benefits of load testing −

  • Identification of performance constraints prior to production

  • Reduces the danger of system downtime by increasing the system's scalability.

  • Failure costs are lower.

  • Customer satisfaction should rise.

Load testing's drawbacks include −

  • To use load testing tools, you'll need to know how to program.

  • Because the price is based on the number of virtual users supported, tools might be costly.


Load testing is a kind of software testing that examines the execution of a system under real-world load conditions.

Load testing usually improves the application's performance bottlenecks, scalability, and stability before it goes into production.

This testing aids in determining an application's maximum working capacity as well as system bottlenecks.

Loading testing is critical since failure to do so can result in financial losses.

Updated on: 17-Aug-2021

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