In my application I have a homegrown framework which maps all the requests to a central ControllerServlet (nothing fancy, it has the basic functionality of almost any framework). I have to implement a Publisher-Subscriber messaging exchange feature and I decided to use Servlet 3.0's asynchronous methods.
The current ControllerServlet and AuthenticationFilter are not setted as asyncSupported. I could either implement a second CotrollerServlet for all the async processing or declare the existing ControllerServlet as asyncSupported=true (even though there are requests that do not need async processing ).
... for an application to use the asynchronous feature, the entire request processing chain must have the have this attribute set either through the annotation or in its deployment descriptor ... - source
From here I understand that I have to declare the AuthenticationFilter as asyncSupported=true (and again there are cases when the async is not needed).
Is there any downsides of declaring servlets and filters as asyncSupported=true even though they also map requests that do not need async processing? Will there be any scalability problems?