Concurrent add on non threadsafe HashSet - what is the worst that could happen?

Question

Situation:

Multiple Threads are only adding values to a non threadsafe java.util.HashSet and no other operation is done on the Se

Answer 1

The worst that can happen (besides an erroneous state of course) is probably an infinite loop when adding a value, blocking one of your threads.

See Paul Tyma article for more information on this case.