It is inevitable that high traffic websites will cause a server stress. CPU and memory loads will rise, and it could affect performance. If you are not careful, it could even bring your server and all of its websites to a halt. Therefore, it is imperative that you have at least a general idea of how much load your server can actually take so that you can do your best to keep the stress below the maximum threshold. A server stress test may be just what you need.
One free and open source solution for stress testing Apache servers is called “ab“, which stands for “Apache Bench”. Designed to tell you how well your Apache installation performs under stress, ab can reveal the number of requests per second your Apache web server is capable of serving.
ab will tell you the time it takes for the test to complete, the number of completed requests, the number of failed requests, the total amount of data transferred, requests per second, time per request, the transfer rate, and many other important facts about your server after the stress test.
You can run ab from your server command line without much difficulty, and the output can either go directly to the screen or to a file.