How many instances of an Action class are created in Struts 1.x

Question

I was searching to know the number of instances created per Action class in Struts 1.x, then I found that it is a Singleton. But I have a doubt: In the action mapping section of struts-config.xml we define the action tag, where there is a scope variable. In that scope variable we can put the value as request, session etc. I wonder that if Action class is a Singleton, then what does this scope variable signify? Does the number of instances per Action class depend upon the scope variable, i.e. if scope is set to "session" the number of instance created depend upon the number of user connected?

Answer 1

The "scope" attribute specifies the scope of the ActionForm only. This allows wizard-like session-based forms to span action mappings, or request-based forms that last only a single request.

There is a single Action instance per mapping (in contrast to an instance per-request, as some frameworks do). Actions should be treated like servlets, and written with thread-safety in mind.