Uninitialized object leaked to another thread despite no code explicitly leaking it?

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Here is what I think: because b is not final, the compiler is free to reorder the operations as it likes, right? So this, fundamentally is a reordering issue and as a result a unsafe publication issue Marking the variable as final will fix the problem.

More or less, it is the same example as provided here in the Java memory model docs.

The real question is how is this possible. I can also speculate here (since I have no idea how the compiler will reorder), but maybe the reference to B is written to the main memory (where it is visible to the other thread) BEFORE the write to x happens. In between these two operations the read happens, thus the zero value

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