php设置了session存储路径为redis后，php的fpm崩溃了

<code><?php namespace Session;

use SessionHandlerInterface;

class MySession implements SessionHandlerInterface {
    private $redis;

    private function connect() {
        if(!$this->redis) {
            $cfg = [
                'scheme' => env('REDIS_SCHEME', 'tcp'),
                'host' => env('REDIS_HOST', '127.0.0.1'),
                'port' => env('REDIS_PORT', 6379)
            ];
            $this->redis = new \Predis\Client($cfg);
        }
    }

    /**
     * Close the session
     * @since 5.4.0
     */
    public function close()
    {
        $this->redis->quit();
        return true;
    }

    /**
     * Destroy a session
     * @since 5.4.0
     */
    public function destroy($session_id)
    {
        $this->connect();
        return $this->redis->del($session_id);
    }

    /**
     * Cleanup old sessions
     * @since 5.4.0
     */
    public function gc($maxlifetime)
    {
        return true;
    }

    /**
     * Initialize session
     * @since 5.4.0
     */
    public function open($save_path, $session_id)
    {
        return true;
    }

    /**
     * Read session data
     * @since 5.4.0
     */
    public function read($session_id)
    {
        $this->connect();
        return $this->redis->get($session_id);
    }

    /**
     * Write session data
     * @since 5.4.0
     */
    public function write($session_id, $session_data)
    {
        $this->connect();
        $expire  =  configure('Ymf.Account.expire');
        if(is_int($expire) && $expire > 0) {
            $result = $this->redis->setex($session_id, $expire, $session_data);
            $re = $result ? 'true' : 'false';
        }else{
            $result = $this->redis->set($session_id, $session_data);
            $re = $result ? 'true' : 'false';
        }
        return $re;
    }
}</code>

这是我的代码，怎么调试哪里出错了

回复内容：

<code><?php namespace Session;

use SessionHandlerInterface;

class MySession implements SessionHandlerInterface {
    private $redis;

    private function connect() {
        if(!$this->redis) {
            $cfg = [
                'scheme' => env('REDIS_SCHEME', 'tcp'),
                'host' => env('REDIS_HOST', '127.0.0.1'),
                'port' => env('REDIS_PORT', 6379)
            ];
            $this->redis = new \Predis\Client($cfg);
        }
    }

    /**
     * Close the session
     * @since 5.4.0
     */
    public function close()
    {
        $this->redis->quit();
        return true;
    }

    /**
     * Destroy a session
     * @since 5.4.0
     */
    public function destroy($session_id)
    {
        $this->connect();
        return $this->redis->del($session_id);
    }

    /**
     * Cleanup old sessions
     * @since 5.4.0
     */
    public function gc($maxlifetime)
    {
        return true;
    }

    /**
     * Initialize session
     * @since 5.4.0
     */
    public function open($save_path, $session_id)
    {
        return true;
    }

    /**
     * Read session data
     * @since 5.4.0
     */
    public function read($session_id)
    {
        $this->connect();
        return $this->redis->get($session_id);
    }

    /**
     * Write session data
     * @since 5.4.0
     */
    public function write($session_id, $session_data)
    {
        $this->connect();
        $expire  =  configure('Ymf.Account.expire');
        if(is_int($expire) && $expire > 0) {
            $result = $this->redis->setex($session_id, $expire, $session_data);
            $re = $result ? 'true' : 'false';
        }else{
            $result = $this->redis->set($session_id, $session_data);
            $re = $result ? 'true' : 'false';
        }
        return $re;
    }
}</code>

这是我的代码，怎么调试哪里出错了