Stress testing is a complex test in which testing is conducted under reduced machine and system resources conditions. The resources that undergo stressing may include internal memory, CPU availability, disk space, and network bandwidth. Stressor utility is generally used to reduce internal resources.
In principle, stress testing tries to break the software by either overwhelming the software with too many tasks. The concept behind stress testing is to let the system fail intentionally to see how it will recover over time. This test will let the software developer know about ability of the software application to recover from adverse situations.
The test induces different variables in the form of creating chaos and thus the results could be extremely unpredicted. Stress test is conducted for a number of reasons such as:
- Doubling the baseline resources for the http connections or the concurrent users
- Shutting and restarting the different ports on the network, such as the routers and the switchers, on a random basis
- Shutting database out of the internet connection and then restarting it immediately
- The RIAD array is rebuilt even when the system is still running
- Running different and simultaneous tasks in the memory, disk, CPU, and network that will consume the software memory and resources
In other words, stress testing is the intricate process of finding out the ability of a computer system, network or related programs to ensure a particular level of effectiveness under conditions that are favorable or useful. You can conduct this test in a laboratory by measuring the frequency of errors and system crashes. Stress testing is performed in combination with performance testing.
When performing a stress test, testers will create or induce an adverse ambiance and maintain it throughout the test. Actions that are performed might include:
- Running a number of resource intensive applications simultaneously on a single computer.
- Planning to hack a computer to us it as a zombie or to distribute spam
- Spamming the system with unwanted e mail messages
- Making an attempt to connect to a web site by using different methods
There are many other ways to break the system; software developers can device creative ways that will enable them to test the tolerance and the recoverability of the software. However, you may need to understand that stress test does not end with breaking open the software application. Rather, it is done to observe how the software will react to the stress as it tries to withstand it.
In case the software application fails the stress testing, there is still an opportunity for software developers to see how the software will react as it fails midway. Software developers will be able to see whether the software will immediately crash or whether it would try to save existing files, for immediate recovery at a later stage. This test also provides an idea to know if the system will hang, freeze, or provide some signals about the impeding hanging.
In addition, software developers will also determine if the software has the capacity to save files and folders from its last failed operation. Likewise, they would also know whether the software actually provides coherent error messages for the users to enable them to understand why the system fails.
From the definition of stress testing, we can see that the amount of tasks that software has to do in the test is enormous. Stress testing is important because it enables software developers to understand how the software will react to conditions of stress. However, stress testing does not usually uncover existing bugs or errors in the system.
You can conduct this test when resources are snatched away from the software. Testers call this method as negative testing, because instead of overwhelming the software with tasks, you are reducing the resource to determine, if the software function properly when this kind of situation occurs.
The stress testing is also conducted by adding scripts in different sectors of the system. The scripts used usually come from regression suite, and with usage of such scripts, the hammering of the system occurs until such a time when the entire system reaches its breaking point.
Stress testing provides you a number of great benefits and advantages. The most significant benefit of stress testing is that you can check the application to see whether it works under any type of stress. Stress testing can uncover many loopholes or weaknesses like memory leaks and even race conditions. Race conditions are the conflicts you will sometimes see, when two tests run concurrently.
A memory leak usually occurs when the test uses the allocated memory and it does not return the said memory space for the memory allocation. This will lead to system failure, as the available memory is eaten up completely. Stress testing may not be a proper type of software testing system. In many cases, many different tests are capable of knowing a software application’s ability to perform well in a real-time ambiance.
Stress testing can provide you with the necessary data that is hard to find anywhere else.
Some of the information data provided by stress testing are:
The measurement – You may need to find more information about the systematic failure of the system and the reasons for it. Stress testing may not verify the codes or the reasons for the system to behave in an erratic way.
Failure resolution – Stress testing can help you control and manage the sheer numbers of bugs. If you correct those errors, the system will not spawn any more errors. Running a debugger program at the start of the testing phase will eliminate the need to fix these bugs.
The load profile – Load profile is important information that you can get from stress testing. Load profiling will keep the system busy throughout the length of testing stage.
The frequency duration – There are two types of frequencies in stress testing; the first is the “short haul” wherein the software is run for approximately 8 hours for analysis. On the other hand, the “long haul” usually takes around 120 hours or 5 days to complete. The short haul stress testing is conducted before the long haul, because the software needs to pass the former before it can move on to the latter.
Development cycle – You will also know the expected development cycle in stress testing, because you will be able to estimate the time during which the entire software can be developed. Many factors influence this cycle such as whether the software will pass the short haul testing or not. If the software passes the short haul testing in its early stages, then there is a good chance that it will be finished faster.
Execution infrastructure – This is a very critical issue in stress testing. In stress testing, the software developer does not care, if the server will be affected by the stress test, because he is only concerned about the software’s response to stressors.
Stress testing is as important test because it allows software developers to know about the software’s functionality and capability to handle different tasks at the same time. However, its scope it quite limited. It just measures the overall response of the software to different stressors, rather than measuring and monitoring it incrementally.
Stress testing should be conducted on a software application. It is interesting to find out that both load testing and stress testing uses the same kind of testing techniques even though their goals are different. You should not mistake load testing for software testing because these two will always yield different results.
Stress testing is an unusual testing procedure that is truly dynamic and interactive. With this test, you can determine the extent of ability of the system to tolerate different and variable inputs that are both good and bad.