Even when a program contains only a single thread running on a single processor, a synchronized method call is still slower than an unsynchronized method call.
即使一个程序只包括一个在单一处理器上运行的单线程，一个同步的方法调用仍要比非同步的方法调用慢。
2
If another virtual processor needs that lock and has excess cycles, it confers those to the first processor through this call.