What about the Fsockopen non-blocking mode of the conversation? Why is it still blocking?

What about the Fsockopen non-blocking mode? Why is it still blocking?

function Fsockopen_test () {
    $hostname = ' m.cn ';
    $url = '/test/1.php ';
    $fp = Fsockopen ($hostname, $errno, $ERRSTR, 5);
    if (! $fp) {
        echo "$errstr ($errno)";
        return false;
    }
    Stream_set_blocking ($fp, 0);//Open the non-blocking mode as stated in the manual
    
    $header. = "Host: $hostname \ r \ n";
    $header. = "connection:close\r\n\r\n";//Long connection closed
    Fwrite ($fp, $header);
    Fclose ($FP);
}
Fsockopen_test ();

The code inside the requested/test/1.php:

Sleep (6);
$fp  =  fopen ('./data.txt ',  ' W ');
Fwrite ($FP, 111);
Fclose ($FP);

Through the browser console to see the actual or will wait for the test/1.php execution, this side only refresh. What is this for?
------Solution--------------------
Yes, no problem.

echo Date (' y-m-d h:i:s '), Php_eol;
Fsockopen_test ();
echo Date (' y-m-d h:i:s '), Php_eol;

can see no delay

