Two seconds is plenty of time.

dlserver/main.go

@@ -208,7 +208,7 @@ func QuitHandler(w http.ResponseWriter, r *http.Request) {
 	}
 	fmt.Fprint(w, "BYE!\n")
 	go func() {
-		time.Sleep(10 * time.Second)
+		time.Sleep(2 * time.Second)
 		os.Exit(0)
 	}()
 }