cas(V, Expected, NewValue)CPU原语支持ABA问题可了解Unsafe.classUnsafe = c c++指针Compare And Set cas(V, Expected, NewValue)v:你当前值E：V的期望值NEW：if (V == E) V = NEW CPU原语支持 ABA问题V值为1，然后改为2，又变回1如果是基础类型无所谓 可了解Unsafe.class Unsafe = c c++指针
