package main
import "fmt"
func main(){
    fmt.Println("c")
     defer func(){ // 必須要先聲明defer，否則不能捕獲到panic異常
        fmt.Println("d")
        if err:=recover();err!=nil{
            fmt.Println(err) // 這里的err其實(shí)就是panic傳入的內(nèi)容，55
        }
        fmt.Println("e")
    }()
    f() //開始調(diào)用f
    fmt.Println("f") //這里開始下面代碼不會再執(zhí)行
}
func f(){
    fmt.Println("a")
    panic("異常信息")
    fmt.Println("b") //這里開始下面代碼不會再執(zhí)行
    fmt.Println("f")
}

func TestPanic(t *testing.T) {
	defer func() {
		if err := recover(); err != nil {
			println("recovered")
		}
	}()
	subFun()
	subFun()
}
func subFun() {
	println("subFun")
	panic("subFun panic")
}

func subFun(i int) {
	fmt.Println("subFun,i=", i)
	panic("subFun panic")
}
func TestSubGoPanic(t *testing.T) {
	defer func() {
		if err := recover(); err != nil {
			println("recovered2")
		}
	}()
	go subFun(3)
	subFun(4)
	println("finish")
}

func BenchmarkSubFunWithError(b *testing.B) {
	for i := 0; i < b.N; i++ {
		go subFunWithError(i)
	}
}
func BenchmarkSubFunWithRecover(b *testing.B) {
	for i := 0; i < b.N; i++ {
		go subFunWithRecover(i)
	}
}
func subFunWithRecover(i int) {
	//fmt.Println("subFun,i=", i)
	defer func() {
		if error := recover(); error != nil {
			//println("subFunWithRecover_recovered")
		}
	}()
	time.Sleep(time.Second)
	panic("subFun panic")
}
func subFunWithError(i int) error {
	//fmt.Println("subFun,i=", i)
	time.Sleep(time.Second)
	return errors.New("subFunWithError")
}
BenchmarkSubFunWithError-12               673920              1992 ns/op             489 B/op          3 allocs/op
BenchmarkSubFunWithRecover-12            1000000              1229 ns/op             240 B/op          2 allocs/op