Logout from all sub-domains on logout

Hi,

I am working on such functionality that when I login to one sub-domain it logins to all other sub-domains I have.

I Used following code in web config :

‘user’ => [

            'identityClass' => 'app\models\User',


            'enableAutoLogin' => true,


            'identityCookie' => [


                  'name' => '_identity',


                  'domain' => '.example.com',


                  'path' => '/',


                  'httpOnly' => true,


             ]


        ],


        'session' => [


          //'savePath' => '\app\session',


          'cookieParams' => [


            'domain' => '.example.com',


            'path' => '/',


            'httpOnly' => true,


            'secure' => false,


          ],


        ],

This works seamlessly and allows to login to all sub-domains at a time.

But when I logout from any sub-domain, system does not logout user from all sub-domains.

I need to logout from all sub-domains at a time when user logout from any of sub-domain.

What do I need to do? Is there any problem in my config code?

Please need help.