runtime

package main

import (
	"fmt"
	"runtime"
)

func main(){
	go func() {
		for i:=0;i<5;i++{
			fmt.Println("go routine")
		}
	}()
	for j:=0;j<2;j++{
		runtime.Gosched() //如果不加这句，那么在主协程执行完毕，子协程还没来得及执行，程序便结束了
		fmt.Println("main routine")
	}
	/*
	go routine
	go routine
	go routine
	go routine
	go routine
	main routine
	main routine
	 */
}

package main

import (
	"fmt"
	"time"
)

func test(){
	defer fmt.Println("ccc")
	return
	fmt.Println("ddd")
}

func main(){
	go func() {
		fmt.Println("aaa")
		test()
		fmt.Println("bbb")
	}()
	time.Sleep(time.Second)
	/*
	aaa
	ccc
	bbb
	 */
}

package main

import (
	"fmt"
	"runtime"
	"time"
)

func test(){
	defer fmt.Println("ccc")
	runtime.Goexit()
	fmt.Println("ddd")
}

func main(){
	go func() {
		fmt.Println("aaa")
		test()
		fmt.Println("bbb")
	}()
	time.Sleep(time.Second)
	/*
	aaa
	ccc
	 */
}

package main

import (
	"fmt"
	"runtime"
)

func main(){
	runtime.GOMAXPROCS(1)//表示使用单核
	for {
		go func() {
			fmt.Print(1)
		}()
		fmt.Print(0)
	}

}

package main

import (
	"fmt"
	"runtime"
)

func main(){
	runtime.GOMAXPROCS(4)//使用4核
	for {
		go func() {
			fmt.Print(1)
		}()
		fmt.Print(0)
	}

}