We came across an issue where we were seeing persistent memory leaks in Hudson.
It appeared to be similar if not the same as the latter part of this thread:

http://www.nabble.com/Possible-memory-leak-in-hudson.remoting.ExportTable-td12000299.html

It was extremely subtle to track this thing down, but I've found the cause of it.

It looks like in the course of handling Unexport and EOF commands, Hudson calls
hudson.remoting.Channel.unexport(oid). This in turn calls
hudson.remoting.ExportTable.unexport(oid), but unfortunately the latter method
expects to be passed the exported object itself, not the oid. It dutifully looks
to see if anyone has exported the Integer oid and when it finds nobody has, it
returns without releasing the reference from the intended Entry.

The fix is simple; introduce an unexportByOid method onto
hudson.remoting.ExportTable and have hudson.remoting.Channel call that instead.
Patch forthcoming.