beginAtTheSameTime

代码说明：

说明：  模拟单道环境下多个进程并发 目的：通过模拟单道环境下多个进程的并发的实验，来加深对进程并发的理解。(Analog single-channel environment than the process of concurrent Objective: Simulation of single-channel environment than the process of concurrent experiments, to deepen their understanding of the process of understanding concurrency.)