Thanks, but the above 2 link don't help
In fact the problem is nit about serialization, it is because in the class "AjaxStateHolder", there has a class variable called "views" which used to store all view state
Then this AjaxStateHolder Object is put to session, in fact only the reference of the Object has put into session, all sequence update to the "views" variable is done "in memory"
However, what I am now doing is separte the user session from Tomcat, all session state will save into the memcache server
Try tell your app server to save all session state into a database and I think this problem will float up