交替打印奇偶数，控制输出到1000，但是经过测试发现有时会输出到1001

[代码地址](https://github.com/crossoverJie/JCSprout/blob/master/src/main/java/com/crossoverjie/actual/TwoThread.java)

**运行结果**：

**分析**
1、当奇数线程在箭头处发生上下文切换
2、偶数线程获取锁，输出1000，并将number.start加为1001，释放锁，判断1001>1000，线程结束
3、奇数线程恢复执行，就会输出1001

Start with src/main/java/com/crossoverjie/actual/TwoThread.java and reproduce the alternating-thread output repeatedly. Inspect the synchronization around the number limit and verify that the program never prints a value above 1000; done means the observed race is eliminated without breaking alternating output.

Written by the indexing model from the issue text.