多进程/线程编程：读者-写者问题。     

1,设置两类进程/线程，一类为读者，一类为写者；  

2,随机启动读者或写者； 

3,显示读者或写者执行状态； 

4,随着进程/线程的执行，更新显示；  -Multi-process/thread programming: Readers- write the problem. 1, set two types of processes/threads, one for readers and one for writers　　2, random start reader or writer　3, shows readers who write execution state　4, with the process/thread of execution, update the display