但是同步还有另一个方面：正如JMM所指定，它强制实施某些内存可见性规则。

But synchronization also has another aspect: it enforces certain memory visibility rules as specified by the JMM.

youdao

注意，在同一个线程的不同方法之间传递对象的引用，永远也不会出现内存可见性问题。

Note that visibility problems never arise when passing references to objects across methods in the same thread.

youdao

可见性则更为微妙；它要对付内存缓存和编译器优化的各种反常行为。

Visibility is more subtle; it deals with the vagaries of memory caching and compiler optimizations.

youdao