我正在使用Golang gorilla / mux包，其中一個例子如下：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)}這似乎很簡單，但我的理解是，在調用時，延遲不會運行（根據 https://gobyexample.com/exit）。我注意到有一個返回的 by ，然后被推遲。我的猜測是，如果在截止日期之前完成，這應該取消上面創建的上下文，但我不明白在最后調用時會如何發生這種情況。任何人都可以幫我看到我錯過了什么嗎？os.Exit()CancelFunc()context.WithTimeout()main()os.Exit()