currenttimemillis

1.But your benchmarking code must handle the possibility that it does no better than System. currentTimeMillis.但是，它可能并不比System.currentTimeMillis好，基准测试代码必须处理这种可能性。

2.In contrast, System. currentTimeMillis merely involves reading a global variable, so it executes extremely quickly, in nanoseconds.相反，System.currentTimeMillis只需要读取一个全局变量，所以执行得非常快，是纳秒级的。

3.A final issue with System. currentTimeMillis that affects even long-running tasks is that it is supposed to reflect "wall-clock" time.currentTimeMillis的最后一个问题是，假设它反映“墙上时钟”的时间，这个问题甚至会影响长时间运行的任务。

4.In reality, System. currentTimeMillis can have ~10-100 times worse resolution. Its Javadocs state在真实环境中，System.currentTimeMillis的分辨率可能会糟糕~10-100倍。