stream_socket_server问题连接重置

First of all I want to apologize if my english is not perfect because i'm not a native english.

I'm facing something that I find weird using stream socket in php; I wanted to run some sort of webserver locally (I know it's not the best way to do it but just for learning).

I'm using this code in my terminal :

<?php
    $server = stream_socket_server("tcp://0.0.0.0:8200");

    while ($conn = stream_socket_accept($server)) {
        echo fread($conn, 1000);
        fputs($conn, "HTTP/1.1 200 OK
Server: PHPserver

bonjour");
        usleep(10000);
        fclose($conn);
    }
    fclose($server);

?>

This works well, I've read that instead of fread I should use stream_socket_recvfrom. But my question is : is if I remove the usleep(10000); this doesn't work anymore my browser sends me an error with ERR_CONNECTION_RESET, but I don't understand why, I think somehow my terminal is closing something to quick ? If someone knows in detail I would be glad to know.

Thanks :)