some servlet calls JSP and in JSP will initialize a servlet below way Servlet1 s=new Servlet1(); s.doPost(request,response); and this in turn calls a jsp and this JSP calls another Servlet.
Firstly you shouldn't instantiate your own Servlets, that should only be done by the container. As long as something eventually provides output to the client it will work fine, except if it causes an infinite loop or any of the container methods on Servlet1 are called.
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