I wasn't refering to Sesions on data, In fact i am not using sessions, i meant it seems that TCP/IP connections are maintained by the JAS when the servlet doesn't find where to write the response(maybe user close the browser).. and because of this the messages java.io.Exception broken pipe... are on logs
does it cause the Server CPU is always in 100%? (this open connections..)
I am pretty sure you are right about the 'java.io.Exception broken pipe' errors being caused because the user closed the browser before the request was served. This was an issue in older versions of WebLogic (at least) and has been fixed for quite some time. What App Server are you using? If the app server chews up resources, far as I know, it is an app server bug.