The term "load testing" is usually used to mean "performance testing". And what then is the proper load testing?
Load testing – these are the same benchmarks, for which the system is exposed to various stresses, with the purpose of this test – to evaluate the system’s ability to function at a certain excess of projected loads in real operation (the system has a "safety margin"). Additionally, load testing determines the performance characteristics (response time, number of transactions, etc.).
Typically, load testing is carried out when loading system 75% of the maximum load during the day.
And why did it have to ask? Well, what system should load a day to operate the same way as when you start – it’s sort of understandable (at the time, like space ships …). Only here, but why would she degrade?
For a long time I did not understand why this kind of testing is necessary. Then he picked up the story of the industry, and everything fell into place. Have you ever heard of such thing as «memory leak»? Oh, did I just see how startled C and C + + programmers. This monster was named in nightmares. And they woke up screaming.
For those who do not know I give the historical background. C and C + + provide excellent opportunities for direct memory management. And require the highest work culture. However, despite all efforts, as a rule, are sections of code, leading to memory leaks. Moreover the memory fragmentation. The result is a slowing down of the system and the need to regularly reboot. For systems 24x7x365 is a real scourge. Judge for yourself, what would need to reboot twice a day, air traffic control system.
I guess it is for such systems and were born in these tests. Ie for systems with the requirements of the class:
Many years ago, began the transition to managed code (Java, C #). And memory management easier. Although, as they say, the curves hands can ruin any system. Simply do not let resources.
And now the findings.
Exercise testing determines whether the degree of degradation of the system within acceptable limits.