System. nano () in Java is slow

System. nano () calls consume 450 nano, which is super slow and 100 times slower than the new Object () operation.

The implementation of System. nanoTime () in linux finally calls the clock_gettime System function.

1 million calls are time-consuming. in java, System. nanoTime () is basically the same as clock_gettime () in C. Therefore, the reason why System. nanoTime () is slow is that the System calls clock_gettime.

When testing System. nanoTime () performance, you must write the following statement: For (int I = 0; I <1000*1000; ++ I ){
Long v = System. nanoTime ();
}

But cannot write like this: For (int I = 0; I <1000*1000; ++ I ){
System. nanoTime ();
}