What is Load Testing?

What is Load Testing? How It Works, Tools, Tutorials, and More

Alexandra Altvater Developer Tips, Tricks & Resources

Performance testing is an important component of the application development lifecycle. Without it, your application could fail miserably in real-world conditions. That’s why we build tools like Retrace to help you monitor application performance, pinpoint and rectify bugs before your code ever gets to production. But performance testing isn’t a single process or method that lets you know whether your app passes or fails; it consists of several specific types of tests and processes designed to measure and evaluate specific performance requirements. Let’s take a closer look at one type of performance testing: load testing.

Definition of Load Testing

It’s a type of performance testing that simulates real-world load on any software, application, or website. It examines how the system behaves during normal and high loads and determines if a system, piece of software, or computing device can handle high loads given a high demand of end users. This tool is typically applied when a software development project nears completion.

How It Works

A load test can be done with end-to-end IT systems or smaller components like database servers or firewalls. It measures the speed or capacity of the system or component through transaction response time. When the system components dramatically extend response times or become unstable, the system is likely to have reached its maximum operating capacity. When this happens, the bottlenecks should be identified and solutions provided.

Performance Testing: Load Testing vs. Stress Testing

Performance testing aims to examine systems behavior and performance, specifically, response time, scalability, speed, and the resource utilization of the software and infrastructure. Load testing is a subset of performance testing. It’s used to check how the systems behave under normal or peak load conditions. Stress testing is another subset of performance testing; it’s applied to check how the system behaves beyond normal or peak load conditions, and how it responds when returning to normal loads.

Load Testing Tools

It’s important to choose a tool that best fits your business needs. Examples of these are WebLOAD, LoadView, and Loadrunner. WebLOAD works on any internet application using Ajax, NET, Oracle Forms, HTML5 and other technologies. LoadView measures performance in real browsers (not headless phantom browsers). Lastly, LoadRunner can manage thousands of users at the same time. For a comprehensive list of many of the tools available today, check out our list of 50 load testing tools.

Possible Use Cases and Examples

Below are a few of the many possible use cases:

  • Airline Website During Promotion Period. Evaluating an airline’s website that will be launching a flight promotion offer and is expecting 10,000+ users at a time.
  • Government Web Portal. Evaluating a website of government agencies, particularly during the filing date of income tax returns when traffic will spike.
  • Running numerous concurrent requests on a server, thus, subjecting the server to a massive volume of traffic.
  • The nonstop transfer of multiple files to and from a hard disk. This could take the form of measuring the speed of laptop with the transfer of 8GB-15GB files to and from a laptop with speeds of 1 mbps.
  • Downloading a huge volume of large files from a company website to test performance.
  • Requesting various jobs on printers in a queue simultaneously.

Benefits of Load Testing

Benefits include the discovery of bottlenecks before production, scalability, reduction of system downtime, improved customer satisfaction, and reduced failure costs. Specifically:

  • Discovery of bottlenecks before deployment. Evaluating a piece of software or a website before deployment can highlight bottlenecks, allowing them to be addressed before they incur large real world costs.
  • Enhance the scalability of a system. It can help identify the limit of an application’s operating capacity. This can aid in determining infrastructure needs as the system scales upward.
  • Reduced risk for system down time. It can be used to ferret out scenarios that can cause a system to fail. This makes it a great tool for finding solutions to high-traffic problems before they arise in the real world.
  • Improved customers satisfaction. If a website’s response times are short even as it scales up to a higher audience, one-time customers will be more apt to revisit.
  • Reduced failure cost. Identifying concerns at the earliest stage possible, especially before launch, decreases the cost of failures. By contrast, after-launch failures can incur exponentially greater costs.

Best Practices for Load Testing

  1. Identify business goals. A strong understanding of future goals for scope and volume will draw clear guidelines to inform the process.
  2. Determine key measures for the application and web performance. Agree on criteria to track. Some criteria include response times, throughput, resource utilization, maximum user load, and business performance metrics.
  3. Choose a suitable tool. Select a tool that best caters to your needs. Some tools include but are not limited to WebLOAD, LoadView, and Loadrunner.
  4. Create a test case. In writing a test case, make sure both positive and negative scenarios are taken into account. Test cases must be accurate and capable of being traced to requirements.
  5. Understand your environment. Consider different types of deployments you might want to test. Create configurations similar to typical production. Test different system capacities like security, hardware, software, and networks.
  6. Run tests incrementally. During these tests, the system will ultimately fail. One key goal is determining what volume results in failure, and spotlighting what fails first.
  7. Always keep end users in mind. The satisfaction of customers and site visitors is crucial to the achievement of business metrics. This plays into their willingness to revisit a site or re-access an application.

Additional Resources and Tutorials

Visit the following tutorials and guides for more information: