使用PHP清除MySQL死链接

<?php
    defile('MAX_SLEEP_TIME', 120);
    $hostname = 'localhost';
    $username = 'root';
    $password = 'password';
    $connect = mysql_connect($hostname, $username, $password);
    $result = mysql_query('SHOWPROCESSLIST', $connect);

    while ($proc = mysql_fetch_assoc($result))
    {
        if ($proc['Command'] == 'Sleep' && $proc['Time'] > MAX_SLEEP_TIME)
        {
            mysql_query('KILL' . $proc['Id'], $connect);
        }
    }

    mysql_close($connect);
?>