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

Question

我使用的是 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)
}

这看起来很简单，但我的理解是当调用os.Exit() 时不会运行延迟（根据https://gobyexample.com/exit）。我注意到context.WithTimeout() 返回了一个CancelFunc()，然后将其延迟。我的猜测是，如果main() 在截止日期之前完成，这应该会取消上面创建的上下文，但我不知道在最后调用os.Exit() 会发生这种情况。谁能帮我看看我错过了什么？

Answer 1

没错，延迟取消函数永远不会被调用。作者可能想指出，在实际应用中，你永远不要忘记取消你的上下文。