Performance Testing vs Load Testing vs Stress Testing: Key Differences

9:15 am
13 Jun 2024

Understanding Performance Testing

As a developer, QA engineer, or DevOps professional, it’s crucial to conduct various performance tests to ensure that every code change or new feature functions correctly and doesn’t break the system.

However, with different types of performance testing available, it’s important to know which ones to use and when.

This guide will help you understand the differences between performance testing, load testing, and stress testing, and how to apply them effectively in your daily activities.

Performance Testing vs. Load Testing vs. Stress Testing

Performance testing encompasses a variety of tests designed to evaluate how your application behaves under different conditions.

Two of the most common types are load testing and stress testing, both of which assess how an application performs when subjected to high usage levels.

Performance testing is an umbrella term that includes various testing activities, such as:

Load Testing
Stress Testing
Soak Testing (Endurance Testing)
Spike Testing
And more

Load testing specifically checks how the system performs under expected load conditions.

For example, if a piece of software/hardware is designed to serve a certain number of users, load testing ensures that it can handle that number efficiently.

Day-to-Day Example: Imagine you are responsible for maintaining an internal enterprise application designed to handle the workload of 500 employees.

Load testing would simulate 500 virtual users interacting with the application simultaneously, ensuring it performs well under these conditions.

This involves:

Simulating the expected load in terms of virtual users or requests per second.
Comparing actual metrics (response time, throughput, error rates, resource usage) with expected outcomes.
Determining if the current build is ready for release

WebLOAD vs. LoadRunner : Which Reigns Supreme?

Load Testing vs. Stress Testing

While load testing simulates real-life usage, stress testing pushes the system beyond its required capacity to identify its breaking points and first bottlenecks.

The goal of stress testing is to find out how much load the system can handle before it starts to fail, and how it fails so you can recognize it coming.

Also you can use that information to create a plan to handle overloads.

Since the overload condition can be created at will, you can also test your plan.

Day-to-Day Example: Suppose you are preparing your e-commerce platform for a major sale event like Black Friday.

Stress testing would simulate a scenario where the number of users drastically increases beyond normal levels to see how your platform holds up.

This helps identify the maximum load your system can handle before performance degrades.

Key points include:

Monitoring how throughput increases with load until it plateaus or decreases due to saturation.
Identifying performance bottlenecks, errors, and potential failures under extreme conditions.

Further Reading: Read our guide for How to Do a Load Test with WebLOAD for a detailed look at how RadView’s WebLOAD specifically helps you conduct load testing.

What is Performance Testing?

Performance testing evaluates a system’s responsiveness, stability, scalability, reliability, speed, and resource usage.

Different types of performance testing provide different insights, helping you determine whether your system meets business and customer needs.

Day-to-Day Example: If you are working on a new feature for a web application, performance testing ensures that the new code doesn’t negatively impact the system’s performance. You might test the feature under various conditions to check response times, stability, and resource usage, ensuring that the feature meets both technical and business requirements.

When to Use Performance Testing

You should run performance tests to check your website and application performance, including servers, databases, and networks.

If you follow the waterfall methodology, conduct tests before releasing a new version.

In agile environments, continuous testing is recommended.

Moreover, some organizations use regression testing as well, comparing the new version to the old version.

Day-to-Day Example: In an agile environment, you might integrate performance tests into your continuous integration pipeline.

Every time new code is committed, automated performance tests run to catch potential performance issues early.

This ensures that each new feature or update maintains the expected level of performance.

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Other Performance Testing Types

Beyond load and stress testing, there are several other performance testing methods to consider:

Soak Tests: Also known as endurance tests, these evaluate how a system performs under sustained load over an extended period.
Example: Running a soak test on a financial application during the end-of-month processing period to ensure it can handle prolonged stress without memory leaks or performance degradation.
Spike Tests: These assess the system’s performance by rapidly increasing the number of requests to stress levels and then decreasing them.
Example: Simulating a sudden influx of traffic to your website from a viral marketing campaign and observing how quickly the system recovers.

How to Do Performance Testing

1. Determine Test Metrics: Identify the metrics to be tested, such as acceptable response time or error rate.

Example: Defining a maximum acceptable response time of 2 seconds for any user request or 1 second for a specific request

2. Decide on Testing Scenarios: Define the scenarios to be tested, like an e-commerce checkout flow.

Example: Creating scenarios for Sales order entry, purchase order entry, general ledger inquiry, and payroll time entry etc.

3. Choose a Testing Platform: Select a suitable open-source/commercial solution, depends on your specific requirements

Example: Using JMeter to simulate user behavior and measure system performance under different load conditions.

4. Configure the Test Script: Build and customize the test script, simulating the expected load and scenarios.

Example: Writing a script in WebLOAD to simulate 1,000 users browsing and purchasing products simultaneously.

5. Run the Test: Execute the tests and monitor the results.

Example: Running the load test script during non-peak hours to minimize disruption.

6. Analyze Results: Identify bottlenecks and performance issues through detailed reports.

Example: Reviewing the test results to find that response times degrade significantly under load, indicating a need for optimization. there are two phases here, did we meet requirements? What is the data telling me about where to look for the problem?

7. Optimize and Retest: Address any issues and retest to ensure performance requirements are met.

Example: Optimizing database queries and running the test again to verify improvements, measurable objectives, like page time, are essential

Bottom Line

Utilizing different performance testing types ensures that you can identify and address potential issues early, maintaining a reliable and efficient application.

By understanding and applying load, stress, soak, spike, and scalability tests, you can comprehensively evaluate your system’s performance and ensure it meets user expectations under various conditions.

Regular performance testing helps keep your application robust, scalable, and ready to handle real-world usage scenarios.