I start to have my doubts (see http://stackoverflow.com/questions/7557156/atomicxxx-lazyset-in-terms-of-happens-before-edges ). On x86, aligned writes are always atomic so this doesn't cause any more issues than other field writes. It appears lazySet has its use when multiple volatile fields need to be written and one doesn't want the barrier to happen at each of them but only at the very end.