Java performance possible memory leak

This is a repost of an existing project. I'm awarding this to an additional freelancer as bug fix is urgent and current freelancer is not available rightnow. This task is to fix a bug inside a client server POS system. In addition to fixing the small bug, the task is to finish up and improve upon the very basic setup of the client/server networking code. Currently clients cannot disconnect from server without server throwing an exception. New information gained suggests this might be a memory leak of some kind as application bloats to considerable size and eventually grinds to a halt. But no memory errors are thrown. I have written a test rig which can be explained to the freelancer concerned. It can produce the problems stated. I'm interested in honest freelancers with some reputation and good feedback. You will need to know how to use SVN, Java Threading, Streams and basic client server architecture. The ability to sort out memory issues might be pertinant.