What is Load Testing?

Load Testing

What is Load Testing?

After the completion of software development process, the team is focused on testing the software using various software testing techniques. Load testing is one such testing technique, that is conducted during the software testing life cycle (STLC) to ensure the stability and reliability of the software product.

Load Testing is the simplest forms of performance testing and is conducted to understand the behavior of the software or application under a specific expected load condition. These loads are based on end users actual demands that are expectable from them, while using the software product.

The principle of load testing is to continuously increase the load on the software, until it reaches its threshold limit, and subsequently evaluating its performance and behaviour, with respect to these increments in the load. It is generally performed to assess how a system behaves under normal and peak conditions, while estimating its maximum capacity to withstand a particular load.

Is Load Testing and Stress Testing Same? : Load Testing vs Stress Testing

Although, both Load testing and Stress testing are the forms of performance testing, but their approach and goals are different. Stress testing is the larger and ferocious version of the load testing. Here are the points of load testing vs stress testing.

Load Testing Stress Testing
1. Load testing is performed with the vision of assessment of system’s behavior under different types of load. 1. Stress testing is performed with the goal of breaking the system, by burdening it with excessive workload, to examine its reliability and robustness.
2. It determines the reliability of the system to endure the maximum capacity of concurrent user load. 2. This type of testing helps determine the stability response time.
3. Identifies defects and bottlenecks in the system to under various workload. 3. Identifies the breaking point of the software.
4. Verifies the performance of the software when there is a sudden upsurge of load. 4. Checks whether the system works accurately under various normal and abnormal conditions.

Volume Testing vs Load Testing vs Stress Testing:

Find differences between volume testing, load testing, and stress testing here.

Key Aspects of Load testing:

During the process of execution, load testing is generally focused on the following features of the software product:

  • Utilization of the resources.
  • Responsiveness of the system.
  • Input and relative output of the system.
  • Maximum load of simultaneous access to system, by the users.
  • Breaking point of the system.
  • Business-related metrics.

Load testing Infographics

Features of Load Testing:

A type of performance testing, to study the behaviour of the system under variant or specific load.

  • Generally, carried out for normal and peak load conditions.
  • It is also a non-functional testing type.
  • Load may include increment in the number of simultaneous users.
  • Carried out in controlled environment, especially in labs to distinguish and measure the accurate capabilities of two different systems.
  • Provides actual experience of simultaneous access to system by multiple users, in real-time environment.
  • Can also be tested, by providing empty or no task to the system, to record the response of system under zero load situation.
  • It stimulates real user load to validate the performance of the software and to ensure optimum user experience.
  • Measures website’s quality of service (QOS) performance, on the basis of actual user experience.
  • The goal of load testing is not to break the target environment but to ensure optimum performance.

How do you do Load Testing?:

After understanding the significance of load testing and its various features, it is vital for us to know the steps involved in the process of load testing, which will help the enable the team to accurately perform the load testing. Hence, the load testing process is described below:

  • Performance Acceptance Criteria Evaluation: The first step of the process involves evaluating the performance acceptance criteria, which is immensely valuable and helps the team members remarkably. These include evaluation of response time, throughput, resource utilization, etc.
  • Identify Critical Scenarios & Metrics: During the second stage of the process, the team is focused on identifying critical scenarios and metrics. This mainly includes identifying business rules and requirements, technology, the expertise required in the application domain, user load, etc. Also, it collects and monitors various metrics like client side metrics, server side metrics, business metrics, and more.
  • Workload Model is Designed: This step of the process involves designing workload model to inject production like pattern in the test. It helps in determining how a application is being utilized in the production environment.
  • Designing Test Scenarios: Once the workload model is designed, the team starts creating test scripts for test execution. This is done by recording business transactions.
  • Identify Target Load: Before executing the test scenarios, it is crucial for the team to identify the target load, which will help determine the effectiveness of the testing. Also, it will ensure multiple users accessing a system get optimum user experience.
  • Test Execution: In this phase of the process the defined load is injected to the server and its behavior is recorded and analyzed by the team. While executing the test scripts and injecting the defined load, the team is required to consider few points like the test environment configuration, load injection server, IP spoofing, etc.
  • Result Analysis: The results derived from the process of testing is analyzed by the team. This is achieved by comparing the results with previous results or iteration and defined metrics.
  • Reporting: Finally, reports are generated by the team that consist a comprehensive summary of the whole process, along with the a proper analysis of the result.

Why Load Testing is Important?

As stated already, load testing is a type of performance testing technique that subjects a software and application to high user load and and analyzes it to determine its limit. With the assistance of this testing, the team is able to verify the scalability of the software, which allows more users to access it. Hence, the various reasons for implementing load testing are:

  1. It helps identify issues and defects in the software product which were not detected by other testing methods.
  2. Determines the operating capacity of an application.
  3. Ensures that the software application meets the performance recognized during the performance testing.
  4. Helps ascertain the number of concurrent users a software system can support.
  5. Identifies bottlenecks and bugs in the software before they occur in production environment.

Load Testing Guidelines:

While performing load testing over a software product and application, it is vital for the team to adopt best practices and to avoid steps that can impact the accuracy as well as the output of testing. Therefore, to help you with this task, mentioned below are some do’s and don’ts of load testing.


  1. Clear browser cache and cookies before recording traffic. When the cache and cookies are not clean, while recording a user scenario, the web browser uses cached data and cookies to process client requests instead of sending data to and receiving responses from the server. However, while running the scenario, Load Complete does not use the cache. It actually sends requests to and receives responses from the server. This may cause a difference between the recorded and actual response codes. Load Complete reports this difference as warnings or errors, and the load test is treated as failed.
  2. Start recording a new scenario from the web browser's start. If you start recording a scenario after you connect to the tested web server and open a few web pages, the playback of the scenario will fail. This will happen because the recorded traffic will not reproduce the authentication procedure, and the tested web server will ignore the simulated requests.
  3. Parameterize scenarios to simulate more realistic load on the server. Parameterizing scenarios involves replacing recorded parameters in the requests with variable values. This way you can make virtual users send user-specific data to the server. This lets you add dynamic behaviours to your scenarios as if they were run by a group of unique human users. Note: Before you parameterize a scenario, carefully explore its requests and responses to better understand what data is being transferred to and received from the server.
  4. Verify user scenarios. Before creating tests on the basis of a recorded scenario, make sure that the scenario is executed successfully for one virtual user. This can help you identify bottlenecks of the scenario and eliminate problems which are not related to the number of virtual users and additional testing conditions.
  5. Arrange user scenarios in your tests so that critical functionality is tested first. And remember to analyse and report on your results!


  1. Do not run tests in real environments. A real environment can have other network traffic, and this may affect test results. To avoid excess data transfer, use a test environment that behaves in the same way as the real environment except that there is no other traffic usage.
  2. Do not try to crash the tested server. The goal of web server performance testing is not to break the server, but to identify web application performance bottlenecks under various loads.
  3. Do not browse web pages during test runs. This may affect the traffic simulation and make the test fail.
  4. Do not overly stress the client test systems. As the aim of this testing is to just verify the performance and stability of the software, it is crucial for you to not stress the client test system, which can lead to its breakdown.
  5. Do not use zero think time. Make sure that think time in your test is based on real-life conditions. Using zero think time does not provide realistic user simulation and puts an abnormal load on the tested server. However, omitting think time can help you determine bottleneck issues.

Advantages of Load Testing:

  • Reduce risk of downtime.
  • Find performance bottlenecks.
  • Reduce costs of failure.
  • Optimize hardware and software costs through accurate capacity metrics.
  • Support continuous process improvement by supporting performance tuning.
  • Increase customer satisfaction
  • Provide tangible statistics to developers
  • Create system benchmarks useful throughout SDLC
  • Improve scalability of the app.

Mobile Load Testing:

Nowadays, mobile apps are used increasingly used by businesses to get excessive amount of traffic, as it offers the users ease of accessing internet from anywhere, among other things. This popularity of mobile apps has made the conducting load testing over mobile a great necessity, so that it can readily face the burden of the enormously increasing traffic, without going in the state of breakdown.

LoadStorm PRO, is one of the effective tool, used to perform load testing on mobile apps, especially, for those, having interaction with the application server through REST or SOAP API Calls. It simulates the traffic environment by making use of HTTP Archive recording(HAR).

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Load Testing Tools: List

Automated testing plays a significant role in load testing. Most of the time, load testing is performed with the help of automated tools. From paid tools to open source and Cloud based tools, various tools are readily available in the market for carrying out this process and deciphering the reliability, quality, and performance of the software.

In nutshell, it can be inferred that, load testing may proves to be an effective approach, to meet the testing needs of the companies, especially for those engaged in e-commerce business, to ensure the unaffected working of their website, on account of continuous increase in load on these websites.


The importance of performance testing and its various types is immense in software testing life cycle (STLC). Performance testing, along with load testing, stress testing, spike testing, volume testing, and more is used by testers to validate various performance related aspects of the software. However to get a comprehensive understanding of performance testing, it is vital for us to understand the significance of its various testing types. Hence, here is a detailed discussion on Load Testing, for your reference.

You can also got through our next article on load testing checklist here.


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