Yii2-Session超时设置无效问题处理

<?php

        $lifeTime = 5;  
        //因修改了SESSION_ID，设置过期时间必须指定session_name

        //session_set_cookie_params($lifeTime, "/");   //默认session name:PHPSESSIONID

        
        //session_start();        
        //setcookie(session_name(), session_id(), time() + $lifeTime, "/");   //推荐使用，必须在session_start() 之后运行
        
        /* if(!isset($_SESSION["signup_sms"])) {
            $_SESSION["signup_sms"] = "wccc1";
            echo "set session. ";
        } */
        
        /* 无效，why?  不能自动识别修改过的PHPSESSIONID？
        Yii::$app->session->setCookieParams([
                "lifetime" => $lifeTime,
                "path" => "/",
            ]
        ); */
        
        //Cannot use isset() on the result of an expression (use "null !== expression" instead)
        if (null == Yii::$app->session->get("signup_sms")){
            Yii::$app->session->set("signup_sms", "wccc2");            
            echo "set session. ";
        }
        setcookie(session_name(), session_id(), time() + $lifeTime, "/");
        print_r(Yii::$app->session->get("signup_sms")."<br>");
        //Yii::$app->session->removeAll();
        //Yii::$app->session->close();
        exit();