Stress Test: how to check the load capacity of the web server
Stress tests are usually performed to check the workload capacity of a web server.
We all know that a web server is made up of software (for example Nginx, MySQL, PHP, …) and hardware (CPU, RAM, disk, network card, …) which uses the HTTP protocol to respond to requests made on the Internet. The machine is instructed to receive HTTP requests from the web and typically respond by sending HTML pages.
the stress test determines the maximum amount of work a server can handle without worsening response times and is never performed under “regular conditions”, but under extreme conditions.
What is a stress test?
A stress test, not to be confused with the load test, is a benchmarking of a website to see how it behaves in critical situations, i.e. with many requests. the web server test itself is a process well known to those concerned with reliability and performance.
Stress testing is defined as the process of verifying hardware or software for its stability under heavy load conditions. This test is performed to find the breakpoint, i.e. a numerical value (in terms of the number of users and server requests etc.) at which the system will break.
During the stress test, the application under test (AUT) is bombarded with a “heavy load” for a set period of time to check the breaking point and to see how error handling is performed.
By testing your web server, you can identify performance bottlenecks and improve your server’s response and load capacity.
While most websites are subject to generally fairly regular traffic levels, there may be occasions when some sites will face heavy loads. Examples of these include online stores or even some government websites.
If your website gets an unexpected spike in visitor numbers in a short period, how well equipped are you to handle it?
For example, a test can simulate an increasing number of simultaneous visitors landing on your site. It will also record the response times of the web server and, more generally, its ability to cope with increasing demands.
The stress test is simply a part of the performance test. It goes along with other tests, such as load test, spike test, endurance test, scale test and volume test. The stress test checks the load limit of a particular web server .
Why a stress test is useful
Here are some technical reasons behind the execution of stress tests:
- To check the behavior of the system under abnormal or extreme load conditions .
- To find the numerical value of users, requests etc., after which the system may become unstable .
- For diagnosis and to be able to manage the error by showing the appropriate messages. It means checking if a correct error message is displayed when the system reaches the breakpoint, i.e. it exceeds the number of requests allowed.
- To be well prepared for extreme conditions and take precautionary measures like code cleanup, DB cleanup, etc.
- To check the data management before the system goes down , for example to see if the data has been deleted, saved or not, etc.
- To verify safety in such breaking conditions, etc.
- Check the load capacity with various combinations of RAM, disk, processor and network , etc.
- Check if the system is functioning as expected when it reaches the limit of manageable HTTP calls.
- Check how the web server response time scales as simultaneous requests increase.
- Check the performance of the app or website when the network is very slow, an error message appropriate for the “time-out” condition should be displayed.
- Check all of the above test cases for a server running more than one application to see if the other application is affected.
