There is no auto-close feature/plug-in in eclipse. Because user opened all the editors manually and he/she has to close these on their wishes but not automatically.
For your problem I suggest you to use Mylyn plug-in so that you can stick to only those editors(context) you frequent used, hiding all other editors, packages, classes etc.
Also there is an eclipse plug-in for pinning editors refer my answer for the post Eclipse - How to pin editor tabs?