模拟进程利用双向邮箱通信 随机生成一个邮箱，两个进程利用该邮箱相互通信，信息的大小与邮箱的大小相同。哪一个进程为发送进程，哪一个进程为接收进程是随机的，由随机函数随机选择。但是若一进程成为发送进程，那么另一个进程只能是接收进程。如果没有申请到资源，就不能建立邮箱，发送进程不能发送消息。如果邮箱中没有空闲单元，发送进程不能够发送消息；如果邮箱中没有消息，接收进程不能够接收消息。-modeling process using two-way communications mail generates a random mailbox, the two processes use of the mail to communicate with each other, information and the size of the same size mail. A process for which this process, a process for which the receiving process is random, random function randomly selected. However, if this process is to be a process, then another process can only be receiving process. If there is no application of resources, the building of mail, send process can send messages. If the mailbox no spare units, sending process can not send messages; If no news mail, the receiving process can not receive information.