post request POST /application/UIDL/?v-uiId=0 HTTP/1.1 halts

I understand that a post request is made on each action that is taken in the application (collapsing a tree table, pushing a button etc). I use tomcat and it’s manager application. I have noticed that one thread performing such a post request get’s jammed (see screenshot). What might be the cause of such a problem? The consequence is that the application freezes for the current user.

Regards Johan