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: