In Struts 2 development, this should be the first configurable value to learn. To enable the Struts 2 development mode, you can significantly increase your Struts 2 development speed by giving auto configuration and properties files reload and extra logging and debugging feature.

The auto reload feature is really a convenient feature. Each time i made changed in properties or XML configuration file, the application is no longer need to restart to take effect.
By default, the Struts 2 development mode is disabled.

Enable the Strut2 development mode

Set the “struts.devMode” value to true, either in Struts properties file or XML configuration file.

struts.devMode = true


 	<constant name="struts.devMode" value="true" />	

Disable the Strut2 development mode

Set the “struts.devMode” to false, either in Struts properties file or XML configuration file.

struts.devMode = false


 	<constant name="struts.devMode" value="false" />	
The development mode is only suitable in development or debugging environment. In production environment, you HAVE TO disabled it. It will caused significant impact on performance, because the entire application configuration, properties files will be reloaded on every request, many extra logging and debug information will be provide also.
Before commit Struts configuration file, just make sure the development mode is turn off. I saw many accidentally commit cases – commit with development mode enable, and someone just grab the source code for QA environment. To be Frankly, QA seldom will do the performance test, they just make sure the functionality are there, and end with a development mode enabled application deployed to the production. Guess what? you will receive many screaming phone calls from clients very soon…


  1. Struts 2 development mode documentation