Not everyone can afford to build their testing tools, and manual testing is high-risk for displaying issues. Another option is open source load testing tools. Open source tools are free, and their functionality is very different from paid tools, as they can quickly and correctly perform basic testing.

Web Server Load Testing and Apache Bench

In February 2021, Netcraft released a web server survey report that included the latest statistical data on top web servers in the market:

Nginx
Apache
IIS
OpenResty
Replace it with
Cloudflare server

Due to the abundance of web server software, let's focus on Apache's benchmark testing tool, which is the second largest and most popular server.

AB (Apache Bench) is a convenient tool for load testing Apache web servers. It comes with Apache installation and generates valuable reports, such as the number of requests the server can process per second.

Load limit

One of the main goals of web server load testing is to measure response time. However, if the web server approaches its limit, it may become unresponsive. Therefore, it is crucial to understand what load limitations are, the reasons behind them, and their symptoms.

Each web server has its predefined load limit, which means that the server can only handle a limited number of client connections. In addition, the web server can only process the maximum number of requests per second. These situations depend on the following factors:

Server settings
Average HTTP request type
Static or dynamic content requests

Cached or compressed content
Number of active TCP (Transmission Control Protocol) connections
Hardware or software limitations for running web servers

Causes of overload

There are many reasons for web server overload. To narrow down the scope, we have listed the most common reasons why IT teams encounter such overload:

Within such a short time interval, thousands of clients have connected to the website

Computer worms and infected browsers and/or web servers. These attacks can sometimes cause millions of computers, browsers, or network servers to be infected, resulting in abnormal traffic

Unfiltered internet robots on large websites

The internet or network slows down, and the services requested by clients slow down. When this situation occurs, the number of connections will significantly increase until the server reaches its limit

Due to maintenance or system failures, the web server is partially unavailable

Symptoms of overload

How to determine server overload before conducting web server load testing? Here are some symptoms of server overload that you should often pay attention to:

Request response delay

HTTP error code

The web server resets or rejects TCP connections before returning any content

Only partial content is returned (behavior is considered a bug)

Anti Overload technology

There is a famous saying that people should "go straight when the boat reaches the bridge". However, before the bridge appears in front of you, you can still plan how to cross it! One method is to master techniques to prevent server overload.

Manage your network traffic by filtering the traffic entering the server, and block any unnecessary traffic through the firewall, such as robots

HTTP Traffic Manager redirects or rewrites requests that contain incorrect HTTP patterns
Bandwidth management
Web cache technology
Practice using different domains to provide different content through separate servers
More hardware resources
Use more web servers