Context.WithTimeout（） 和 os.exit in gorilla/mux

Question

我正在使用Golang gorilla / mux包，其中一个例子如下：

func main() {

    var wait time.Duration

    flag.DurationVar(&wait, "graceful-timeout", time.Second * 15, "the duration for which the server gracefully wait for existing connections to finish - e.g. 15s or 1m")

    flag.Parse()

    r := mux.NewRouter()

    // Add your routes as needed

    srv := &http.Server{

        Addr:         "0.0.0.0:8080",

        // Good practice to set timeouts to avoid Slowloris attacks.

        WriteTimeout: time.Second * 15,

        ReadTimeout:  time.Second * 15,

        IdleTimeout:  time.Second * 60,

        Handler: r, // Pass our instance of gorilla/mux in.

    }

    // Run our server in a goroutine so that it doesn't block.

    go func() {

        if err := srv.ListenAndServe(); err != nil {

            log.Println(err)

        }

    }()

    c := make(chan os.Signal, 1)

    // We'll accept graceful shutdowns when quit via SIGINT (Ctrl+C)

    // SIGKILL, SIGQUIT or SIGTERM (Ctrl+/) will not be caught.

    signal.Notify(c, os.Interrupt)

    // Block until we receive our signal.

    <-c

    // Create a deadline to wait for.

    ctx, cancel := context.WithTimeout(context.Background(), wait)

    defer cancel()

    // Doesn't block if no connections, but will otherwise wait

    // until the timeout deadline.

    srv.Shutdown(ctx)

    // Optionally, you could run srv.Shutdown in a goroutine and block on

    // <-ctx.Done() if your application should wait for other services

    // to finalize based on context cancellation.

    log.Println("shutting down")

    os.Exit(0)

}

这似乎很简单，但我的理解是，在调用时，延迟不会运行（根据 https://gobyexample.com/exit）。我注意到有一个返回的 by ，然后被推迟。我的猜测是，如果在截止日期之前完成，这应该取消上面创建的上下文，但我不明白在最后调用时会如何发生这种情况。任何人都可以帮我看到我错过了什么吗？os.Exit()CancelFunc()context.WithTimeout()main()os.Exit()

Answer 1

你是对的，从不调用延迟取消函数。作者可能想指出，在实际应用中，你永远不应该忘记取消你的上下文。