PHP asynchronous execution method to simulate multi-threading

$fp = fsockopen('localhost',80,&$errno,&$errstr,5);
if(!$fp)
{
 echo "$errstr ($errno) n";
}
fputs($fp,"GET ./test.phprn"); //The path in this place must be correct. It was wrong at the beginning
fclose($fp );

and place the required code in test.php so that it will be executed asynchronously.