Server-Sent Events

I don't know if there is a problem, but I am making a php to javascript feed using Server Sent events instead of ajax. Everything works fine except sleeping on the server side, blocking the event source thread, blocking the webpage thread. I did some pretty simple code for testing and I got the same results.

I'll put the code above.

Server-sent events hang on page flow? its not like ajax that makes asynchronous requests?

Basic question: events sent by the server hang on the stream of code, what I mean is, the page expects the EventSource to keep executing the code, every time eventSouce opens a connection or receives a message. I can see this clearly, when I put in the server side code, my page freezes during sleep, starts for 3 seconds, and then hangs again. When I make an ajax call, the call is asynchronous, so the code keeps running with ajax in the background even if I find myself sleeping on the server side. Hope you can now understand = p

test.php

                    @set_time_limit(0);
                    //send the proper header
                    header('Content-Type: text/event-stream');
                    header('Cache-Control: no-cache');
                    if(function_exists('apache_setenv')){
                        @apache_setenv('no-gzip',1);
                    }
                    @ini_set('zlib.output_compression',0);
                    @ini_set('implicit_flush',1);
                    for($i = 0; $i < ob_get_level(); $i++){
                        ob_end_flush();
                    }
                    ob_implicit_flush(1);

                $startedAt = time();

                do {

              $time = time();
              echo "id: $startedAt " . PHP_EOL;
              echo "data: {\n";
              echo "data: \"msg\": \"$time\", \n";
              echo "data: \"id\": $startedAt\n";
              echo "data: }\n";
              echo PHP_EOL;
                //@ob_flush();
                @ob_end_flush();
                @flush();   
                usleep(0.5*1000000);
                } while(true);

      

        
        
        
      

    

Html

if(!!window.EventSource) {
     var source = new EventSource('test.php');
     source.addEventListener('open', function(event) {
     console.log('open');
  }, false);
    source.addEventListener('message', function(event) {
    var data = JSON.parse(event.data);  
    console.log(event.data);
  },false);
}