Load testing is a process of measuring a computing or software system’s performance while simulating the expected demand those systems are likely to encounter. This is often done in programs where multiple users are accessing the same program at the same time, such as a website which can experience heavy traffic during peak times. There are also instances where load testing is necessary in single user applications as well. While loading large files, running reports or accessing graphic content programs can see a heavy load and its important to see if the program responds in a timely manner and without errors. In either case, the load test is a great way to measure the performance of the system during what is anticipated to be peak demand.
Load testing is conducted once a system is near completion, when most systems are active. This allows the test to simulate multiple users performing a multitude of tasks simultaneously. This is different than the functions testing that occurs during the building process which typically only tests one function or user at a time. The load test process is a useful tool for designers of these systems to anticipate where they may see failures, bottle necks, system lag or other bugs due to high demands on the system, and engineer solutions to mitigate that risk or avoid them all together.
A stress test varies from a load test in that is is designed to bring a system to the point of failure, by putting what is anticipated to be an unrealistically high demand on the system. The stress test pushes the outer reaches of the system’s capabilities to let the engineers know when a system will fail, and analyze just how catastrofic the failure can be. This gives the designers a chance to make adjustments that can make failures less severe and easier to recover from. It is important to note that a load test can become a stress test if it pushes the system to it’s breaking point unexpectedly.
Both types of tests are tools that can be used before bringing a system online to check for potential pitfalls that may exist. Depending on the application one or both of these tests may be necessary to understand how the system will respond to high demand. If you’re looking for additional information on load testing, you can read more (including tutorials) on a variety of sites across the web. Wikipedia, TechTarget, and other similar sites are good places to start you research.