Stress Test ASP.NET Web Application With Free WCAT Tool


Building ASP.NET web applications? Plan to serve thousands of users? Would you like to see how your application would behave [misbehave] under stress?

Use simple-to-use and freely available WCAT tool to generate the load and get detailed report for expected throughput (requests/sec) and other important performance-wise information.

Summary of steps

  • Install WCAT
  • Create configuration files
  • Run the test
  • Examine results

Next section describes each step in details. Note, this post is a how-to, a jump start - not the guidelines or best practices of how to use the tool.

Install WCAT

Download and install Internet Information Services (IIS) 6.0 Resource Kit Tools. For the purpose of our exercise there is no need to install all the tools included with the resources kit, only WCAT.

Create configuration files

There are three textual files one needs to create and configure (you can give any name and extension of your choice):

  • script.txt - this file defines the requests, in other words what pages to request and how to request it. Following is an example of simple script.txt file:

    classId = 1
        Verb = "GET"
        URL = "http://localhost/BankingShmanking/Default.aspx"

  • distribution.txt - defines weights among different requests. For example, if I need to generate request to page1.aspx twice as to page2.aspx, I will define it in this file. In case of loading only one page, the file is meaningless. Following is an example of simple distribution.txt file (1 refers to classId in script.txt file, and 50 is that 50% of the load should got this file which is meaningless since there is only one page to request, thus it will get the whole 100% load):

1 50

  • config.txt - determines the duration of the test, number of clients that will generate the requests against the web application. Following is the example of simple config.txt file:

Warmuptime 5s
Duration 30s
CooldownTime 5s
NumClientMachines 1
NumClientThreads 20

Save the files in "C:\Program Files\IIS Resources\WCAT Controller" folder.

Run the test

To run the stress test open command prompt by opening Run window(Windows + R) type cmd and hit Enter. Change current directory to "C:\Program Files\IIS Resources\WCAT Controller>" and run the following command to test the page hosted on the localhost:

wcctl -c config.txt -d distribution.txt -s script.txt -a localhost

then open second command prompt, change current folder to "C:\Program Files\IIS Resources\WCAT Client" and run the following command to actually launch the virtual client's requests from local machine:

wcclient.exe localhost

Examine results

The results are displayed interactively in the command line windows



The tool also generates log file that includes logged metrics - look for it in "C:\Program Files\IIS Resources\WCAT Controller" folder.

WCAT tool is actively developed by IIS team and recently they released new version of the tool - WCAT 6.3, download it from here, free.