动态设置会话保存路径时出现Symfony2缓存问题

I am trying to set session save path dynamically in Bundle extension class

namespace AdminBundle\DependencyInjection;

class AdminExtension extends Extension{
...
   $sessionDir = $envDir . "session/store/$userDir/__sess";
   $container->setParameter("session.save_path", $sessionDir);
...
}

Symfony caches Extension class

$sessionDir = $envDir . "session/store/12345/__sess";

So it make sessionDir equal to directory of user who make first call.

It works normal for first user but doesn't work for others.

What can I do to solve this problem?

I solved problem by writing my own NativeSessionHandler

class NativeFileSessionHandler extends NativeSessionHandler
{

    /**
     * @param ContainerInterface $container
     */
    public function __construct(ContainerInterface $container)
    {
       ...
        ini_set('session.save_path', $envDir . "session/storefront/$userDir/__sess");
        ini_set('session.save_handler', 'files');
    }

}

services.yml

custom_file_session_handler:
    class: CoreBundle\Session\Handler\NativeFileSessionHandler
    arguments: [@service_container]

config.yml

framework:
   session:
        handler_id: custom_file_session_handler