C#當中使用async和await WaitAll
https://www.cnblogs.com/dcz2015/p/11004585.html
https://www.cnblogs.com/zhaoshujie/p/11192036.html
Task WaitAll和WaitAny源碼
https://blog.csdn.net/ma_jiang/article/details/78648153
https://www.cnblogs.com/caoyc/p/6382528.html