Can the JVM GC move objects in the middle of a reference comparison, causing a comparison to fail even when both sides refer to the same object?

Question

It\'s well known that GCs will sometimes move objects around in memory. And it\'s to my understanding that as long as all references are updated when the object is moved (before

Answer 1

I understand you are asking this question after someone says it behaves that way, but really asking if it does behave that way isn't the right approach to evaluating what they said.

What you should really be asking (primarily yourself, others only if you can't decide on an answer) is whether it makes sense for the GC to be allowed to cause a comparison to fail that logically should succeed (basically any comparison that doesn't include a weak reference).

The answer to that is obviously "no", as it would break pretty much anything beyond "hello, world" and probably even that.

So, if allowed, it is a bug -- either in the spec or the implementation. Now since both the spec and the implementation were written by humans, it is possible such a bug exists. If so, it will be reported and almost certainly fixed.