PHP echo before sleep function, not working

Question

I want output echo in browser (every time) before sleep function execute.

following code is not working

    set_time_limit(0);
    ob_implicit_flush(1);
    ob_start();
    echo "Start<Br>";
    ob_flush();

    for($i=0;$i<10;$i++){
        $randSlp=rand(1,3);
        //echo str_repeat(" ", 1024);
        echo "Sleeping for ".$randSlp." second. ";
        ob_flush();

        sleep($randSlp);
    }
    ob_end_flush(); 

if uncomment str_repeat function than in browser
First time : Start Sleeping for 1 second. Sleeping for 3 second.
Second time : Sleeping for 2 second. Sleeping for 2 second.

and continue...

is possible echo one by one without str_repeat() function, why output doesn't display every time.

Answer 1

Try following code and its work.

header( 'Content-type: text/html; charset=utf-8' );
header("Cache-Control: no-cache, must-revalidate");
header ("Pragma: no-cache");
set_time_limit(0);
ob_implicit_flush(1);
//apache_setenv('no-gzip', 1);
//ini_set('zlib.output_compression', 0);
//ini_set('implicit_flush', 1);
for ($i = 0; $i < 10; $i++) { 
    $randSlp=rand(1,3);
    echo "Sleeping for ".$randSlp." second. ";;
    sleep(1);
    if(ob_get_level()>0)
       ob_end_flush(); 
}

Answer 2

even the output buffer (ob_* functions) do not necessarily give output to browser directly.

First try calling flush() before or after ob_flush().

Second, look if mod_gzip or zlib.output_compression is turned on for example. This will also buffer all output.

If using IIS server and not Apache, there might also be settings in IIS to check.