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

GCs only happen at points in the program where the state is well-defined and the JVM has exact knowledge where everything is in registers/the stack/on the heap so all references can be fixed up when an object gets moved.

I.e. they cannot occur between execution of arbitrary assembly instructions. Conceptually you can think of them occuring between bytecode instructions of the JVM with the GC adjusting all references that have been generated by previous instructions.