php - Codeigniter version 2.0.2 redirect loop issue

I have moved from codeigniter 1.7 to 2.0 and so i replaced MY_Controller to CI_Controller andparent::MY_Controller(); toparent::__construct(); in login controller and from login controller view is loading and in that view I have added exit at start of the file its not a problem occurring due to other files.

Now, by this change my error for controller has gone, but the issue is I am having error for redirect loop.

If I have added exit beforeparent::__construct(); then it is working fine,but If i have added exit afterparent::__construct();,its going to redirect loop.

There is nothing writter in my hook.php

My route php is 

$route['default_controller'] = "login";
$route["404_override"] = "";

 Codigniter version is 2.0.2

 LOGIN FILE ::


  /public_html/projectname/application/controller/login.php

 class Login extends CI_Controller
 {     

 function __construct()
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{ echo "test";exit // Here,its working fine without going to loop

   parent::__construct();

    echo "test";exit // Here this will give redirect loop issue 

}
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}

/public_html/projectname/.htaccess

 RewriteEngine on
 RewriteCond $1 !^(index\.php|resources|robots\.txt)
 RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
 RewriteRule ^(.*)$ index.php/$1 [L,QSA]


 // route.php


 $route['default_controller'] = "login";
 $route["404_override"] = "";
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