Falling beneath the umbrella of performance testing, both load and stress testing play an important role in assessing the availability and performance of your web or mobile applications under expected and extreme load.
While the terms “stress testing” and “load testing” may be used interchangeably within a testing team or organization, the two differ when it comes to their definitions and purpose.
Stress Testing vs. Load Testing
Load Testing: A performance-related testing process that places simulated demand on software, web or mobile applications in order to measure responses and systems’ behavior under both normal and anticipated peak load conditions.
Its purpose: Providing insight into your application and system’s behavior under expected load conditions.
Stress Testing: A testing process designed to push an application’s environment to its breaking point so that QA teams can gain an understanding of the upper limits of capacity within the system.
Its purpose: Stress testing exposes issues that may not appear under normal or even expected conditions. It allows testers to determine the software’s robustness and ensure that the system fails and recovers in an acceptable manner.
Stress Testing: When, Why & How
When to conduct stress tests
Typically during the software development lifecycle, smaller load tests can be run before a big release or after each sprint/iteration. This allows for the detection of issues that may cause larger performance problems during full scale stress testing.
While some Agile organizations are able to run stress tests at the end of sprints before they release to integration or deploy to production, this strategy is NOT recommended for business critical applications.
When your application absolutely needs to perform for end users, you’ll need to run longer peak tests and stress tests during a hardening sprint (or before the release of a new application/update if you’re working in a traditional environment) to truly ensure application performance in production. This becomes especially important for eCommerce apps around big holiday seasons, online tax filing services during tax season, universities during class registration periods, etc.
The biggest takeaway here is that stress testing during a hardening sprint or right before a release is absolutely necessary to ensure that your application’s performance level meets end user expectations.
Benefits of stress testing
Extreme load conditions are rarely seen in production. Therefore, stress testing benefits organizations by revealing application issues that only become apparent under these extreme conditions. Proper stress tests can also help you uncover the following:
- Synchronization and timing bugs
- Interlock problems
- Priority problems
- Resource loss bugs
- Memory leaks
- Data loss & corruption
Utilizing stress testing tools
When approaching stress testing, you’ll want first identify test objectives, key scenarios, the workload you want to apply, and the metrics you’ll be tracking. After you’ve created your test cases, work with a stress testing tool to simulate the required load for each test case and capture performance metrics.
A truly effective stress testing tool will realistically simulate thousands+ of users, analyze your application’s performance and monitor your servers under load.
Reaching the Breaking Point
Stress testing is an essential and beneficial process that provides otherwise unattainable insight into the performance of your web and mobile applications under extreme load. Identifying the potential breaking points in your application will allow you to correct them before they become expensive issues in production.
While extreme load conditions rarely appear in production, never underestimate the potential for their occurrence. To learn more about how you can stress test your web or mobile applications in preparation for peak load conditions, check out our Holiday Readiness Case Study here.