Garbage collection and synchronized visibility

Question

I have read about marking an object as volatile doesn\'t guarantee visibility of it\'s members ( I\'m not saying about thread safety just memory visibility

Answer 1

1. Yes, happens-before relationship will gurantees that. While volatile keyword also builds happens-before relationship between the write thread and the read thread.

Using volatile variables reduces the risk of memory consistency errors, because any write to a volatile variable establishes a happens-before relationship with subsequent reads of that same variable.

2. The java language specification does not mention it, or any specific mechanism about how to implement volatile. So I guess it depends on the specific JVM.