Please note that the timeout parameter has important side-effects on the CPU usage of your script.
Setting the timeout to 0 will make your CPU looping without any time to have some rest and handle other running processes on your system, causing the system load to increase heavily while your script is running.
Personnaly, I use a value of 15 ms for this parameter. this ensures a good listening frequency while letting your system load clear.
Example :
$read = array($ListeningSocket);
$num_changed_sockets = socket_select($read, $write = NULL, $except = NULL, 0, 10);
Hope this helps.
