转载 https://www.jianshu.com/p/f4454164c017 作者 占小狼 最简单的东西,往往包含了最复杂的实现,因为需要为上层的存在提供一个稳定的基础,Object作为java中所有对象的基类,其存在的价值不言而喻,其中wait和notify方法的实现多线程协作提供了保证. public class WaitNotifyCase { public static void main(String[] args) { final Object lock = new Objec…
1.数据集 A表数据: 1 a 2 b 3 c B表数据: 1 aa1 1 aa2 2 bb1 2 bb2 2 bb3 4 dd1 2.join的分类 inner join left outer join right outer join full outer join left semi join 3.集中join的结果 A inner join B: 1 a 1 aa1 1 a 1 aa2 2 b 2 bb1 2 b 2 bb2 2 b 2 bb3 A left outer join B:…
转自: http://aredko.blogspot.com/2014/02/knowing-how-all-your-components-work.html In today's post we will try to cover very interesting and important topic: distributed system tracing. What it practically means is that we will try to trace the request…