When I connecting with $html = file_get_html("www.example.com") and server have opened port 80 but is busy, function file_get_html() is witing on and on and on.
file_get_html() not have a timeout.
This kind of timeout error can be corrected are likely to increase the time limit using ini_set. Additionally, you may also need to include set_time_limit.
ini_set( 'default_socket_timeout', 120 );
set_time_limit( 120 );