Golang语言--Coroutine可能存在的死锁

直接上代码：

1. 第一种情况， 如果没有select{}， main 主线程不会等待coroutine运行，导致coroutine得不到机会运行。

You are requesting eventual scheduling (using the two go statements) of two goroutines and then you exit main without giving the scheduler a chance to do anything.

有了select， 程序正常运行。

2. coroutine有机会运行，但是会发生死锁， fatal error: all goroutines are asleep - deadlock!

The goroutine executing func1 exited, ditto for func2. The main goroutine is blocked with no hope to recover while no other goroutine can be scheduled.

3. 第三种情况， 正常运行。

4. 实现上面的目的的另外一种方法：