I'm not sure what you are looking for here. Struts 1 and 2 have different approaches to actions. Since Struts 1 only creates one instance of a particular action, the programmer must always keep
thread safety in mind. For example, if one uses an instance variable in an action, it can create a race condition as multiple threads each set the variable to their own particular value.
Since Struts 2 creates an action instance for each request, this is one less thing the developer has to worry about.