Not every user of a modern computer system in everyday work is faced with the concept of “stress testing”. Basically, it is familiar to web developers and all those who use resource-intensive programs. Nevertheless, sometimes knowledge in this matter can be useful to ordinary users. Let's try to figure out why all this is needed.
Load testing: types and goals
First of all, it is necessary to clearly distinguish between the types of such tests. Conventionally, they can be divided into two classes: checking the computer hardware at the maximum possible or excessive load on each component and testing software (websites with forecasting elements, individual programs, etc.).
It goes without saying that testing sites is directly related to checking the health of the servers that host the information, as well as to virtual web servers that are created in the process of working with specialized programs like Denwer.
Programs for load testing and their tasks
As you can see, the relationship here is very strong. And if we talk about hardware, the system of load testing using special utilities allows you to accurately identify potential problems when working, so to speak, in extreme situations. The simplest example . Modern computer games with their requirements can easily load the system to such a state that it generally stops working. Therefore, before installing such software on a computer, you can conduct a series of tests to determine whether the filling can "pull" the game. Based on the results, a decision is made to install the program. In principle, the same applies to applications involving complex mathematical calculations and design work, since the load on the same processor or RAM compared to the normal state of the system can be exceeded several times.
As for the second class, testing the site and server can act as a universal tool for predicting their behavior in real-life conditions. For example, it can be an emulation of a simultaneous access request of a large number of users. As you know, DDoS attacks operate on this principle when the server or site does not have time to process too many calls. Load testing of a server or site will be considered in more detail a little later. In the meantime, let's get down to computer hardware. This applies not only to home or work terminals, but also to real physical server systems.
Processor test
Let's start with the heart of any computer - the central processor. It is no secret that it is precisely the malfunctions in his work that in most cases lead to the most sad consequences. Very often this is due to overheating. Stress testing allows him to create extreme conditions. And then you can see how this will affect his work.
It goes without saying that carrying out load testing of this type involves the use of certain utilities. Today they can be counted hundreds and thousands. But, according to most experts, the leader in this area is the Prime95 application, which can be applied to processors and RAM slots. But the main direction is testing the processor chipset.
When using the utility for a start, it is recommended to close all active applications and turn off the automatic hibernation (sleep) mode so that the computer does not accidentally turn off during the scan. Now you need to simulate the most severe conditions for the processor (and the program can do this like no other, really putting the chips in the most difficult conditions). The test itself is activated from the options menu, where the Torture Test section is selected. There will be indicated the types of operations. The most interesting tests here are Blend (simultaneous load on both the processor and the RAM), as well as Small FFT and Large FFT (increase in processor load due to unloading of RAM).
How to determine that load testing was successful? There is no consensus here, but it is believed that if no errors or malfunctions of the chip were observed for at least 4 hours, this component is quite resistant to excessive loads. But it also happens that failures can appear much later, so if you have a fair amount of time, it is better to increase the testing period to 24 hours (errors can appear after half a day of work).
Testing RAM
No less important is the load testing of the "RAM", which performs the functions of the so-called second violin. For this, the Memtest86 + application, which is by far the best, is best suited.
To work correctly with its help, you need to create a boot disk or flash drive and load the computer terminal from just such a medium. After activating the test, it will take quite a long time to complete it. You can just leave the computer overnight. That should be enough.
Determining graphics behavior
With graphics, it’s also worth a test, because video adapters under excessive load are often the cause of computer failures. The ideal tool here is the FurMark program.
This utility is able to heat the graphics chip much more than any three-dimensional game with system requirements above the average will do. As practice shows, conditions are created such that the video card can begin to fail already in the period from 15 to 30 minutes after the start of testing.
In addition, you can use special utilities designed for specific games. For example, test applications like Alien vs Predator, STALKER, or something else are very good. As a rule, they are distributed completely free of charge, and with their help you can precisely determine how the system will behave after installing the original game package.
What is testing servers and sites for?
Now a few words about what is testing the site and the web server. One aspect (DDoS attacks) has already been said. Now let's look at this issue from the other side.
To some extent, tests of this type themselves can even be attributed to marketing tools for predicting user behavior. So, for example, you can simulate the behavior of a certain number of (maximum / peak) people upon entering the site, find out how many pages can be viewed, whether e-mail will be involved, for example, in the process of ordering goods, how information can be used to identify visitors, will allow is channel capacity to provide simultaneous access to users of the site at any given time, it will demand confirmation of user credentials by a third party (naprime When you enter a credit card number), how effective will be the introduction of Java-applets or using a secure https connection, and so on. D.
Web server (software) test questions and generated Internet resources
In principle, almost the same tasks are set and load testing of the server. However, the emphasis here is on a purely non-technical aspect. Tests make it possible to identify whether several users can have the same IP, to specify the response time to requests sent, to find out how the whole system will respond to a secure or insecure connection, what will be the access speed if too many requests are sent at the same time, etc. .
In this case (both for the site and for the web server), many advise using a powerful package called OpenSTA (System Architecture Test), which allows not only checking, but also breaking down tasks into components for each individual structure element using the tool creating and modeling scripts Script Modeler. It is noteworthy that after creating such a model, you can even check the connection using the SSL protocol (the so-called name server must be launched). In addition, the results can be saved in the Repository Host section, and the tests can be grouped into appropriate groups.
What is the result?
In principle, this is a very brief information on the issues of load testing, because the tests themselves, as well as the programs that allow them to be carried out, can be found a lot. Let's just say: the most popular utilities are presented here and the essence of the issue is considered. It seems that after acquaintance, any user will advance at least a little in understanding issues related to stress testing.