123go小窍门让Go无路可go的十个方

本节有且仅有一个目的，那就是让Go程序遇到“panic”。

1.数组/切片索引越界

func main() { names := []string{ "煎鱼", "eddycjy", "Go编程之旅", } name := names[len(names)] fmt.Printf("name: %s", name)}

运行结果：

panic: runtime error: index out of range [3] with length 3goroutine 1 [running]:main.main() /Users/eddycjy/go-application/awesomePanic/main.go:11 +0x1b

2. 空指针调用

type User struct { Name string}func (u *User) GetName() string { return u.Name}func main() { s := &User{Name: "煎鱼"} s = nil s.GetName()}

运行结果：

panic: runtime error: invalid memory address or nil pointer dereference[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1056f62]goroutine 1 [running]:main.(*User).GetName(...) /Users/eddycjy/go-application/awesomePanic/main.go:8main.main() /Users/eddycjy/go-application/awesomePanic/main.go:14 +0x2

3.过早关闭HTTP响应体

func main() { resp, err := http.Get("https://xxx") defer resp.Body.Close() if err != nil { log.Fatalf("http.Get err: %v", err) }}

运行结果：

panic: runtime error: invalid memory address or nil pointer dereference[signal SIGSEGV: segmentation violation code=0x1 addr=0x40 pc=0x123d4d3]goroutine 1 [running]:main.main() /Users/eddycjy/go-application/awesomePanic/main.go:10 +0x63

4.除以零

func divide(a, b int) int { return a / b}func main() { divide(1, 0)}

运行结果：

panic: runtime error: integer divide by zerogoroutine 1 [running]:main.divide(...) /Users/eddycjy/go-application/awesomePanic/main.go:4main.main() /Users/eddycjy/go-application/awesomePanic/main.go:8 +0x12

5.向已关闭的通道发送消息

func main() { ch := make(chan string, 1) ch <- "煎鱼" close(ch) ch <- "Go编程之旅"}

运行结果：

panic: send on closed channelgoroutine 1 [running]:main.main() /Users/eddycjy/go-application/awesomePanic/main.go:7 +0x7d

6.重复关闭通道

func main() { ch := make(chan string, 1) ch <- "Go编程之旅" close(ch) close(ch)}

运行结果：

panic: close of closed channelgoroutine 1 [running]:main.main() /Users/eddycjy/go-application/awesomePanic/main.go:7 +0x71

7. 关闭未初始化的通道

func main() { var ch chan string close(ch)}

运行结果：

panic: close of nil channelgoroutine 1 [running]:main.main() /Users/eddycjy/go-application/awesomePanic/main.go:5 +0x2a

8.未初始化map

func main() { var m map[string]string m["Go编程之旅"] = "一起用Go做项目"}

运行结果：

panic: assignment to entry in nil mapgoroutine 1 [running]:main.main() /Users/eddycjy/go-application/awesomePanic/main.go:5 +0x4b

9.跨协程的“恐慌”处理

func main() { go func() { defer func() { if err := recover(); err != nil { log.Fatalf("recover err: %v", err) } }() handle() }() time.Sleep(time.Second)}func handle() { go divide(1, 0)}func divide(a, b int) int { return a / b}

运行结果：

panic: runtime error: integer divide by zerogoroutine 17 [running]:main.divide(0x1, 0x0, 0x0) /Users/eddycjy/go-application/awesomePanic/main.go:34 +0x40created by main.handle /Users/eddycjy/go-application/awesomePanic/main.go:30 +0x47

10. sync计数为负值

func main() { wg := sync.WaitGroup{} wg.Add(-1) wg.Wait()}

运行结果：

panic: sync: negative WaitGroup countergoroutine 1 [running]:sync.(*WaitGroup).Add(0xc000104000, 0xffffffffffffffff) /usr/local/Cellar/go/1.14/libexec/src/sync/waitgroup.go:74 +0x139main.main() /Users/eddycjy/go-application/awesomePanic/main.go:7 +0x44

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