PHP cannot output principle analysis every second using ob_flush

The example in this article describes the principle that PHP cannot output every second using ob_flush. Share it with everyone for your reference. The specific analysis is as follows:

Function implementation:

The browser outputs a number every second.

php.ini is configured as:

Version 5.3

implicit_flush = off
output_buffering = off

Another: Check whether output_buffering is turned on, you can:

var_dump(ini_get('output_buffering'));

Okay, let’s take a look at this code again:

<?php
  $i = 3;
  ob_start();
  while ($i--) {
    echo $i, "<br />";
    ob_flush();
    flush();
    sleep(1);
  }
  ob_end_clean();
?>

But why: This code cannot be output every second? ?

Cause analysis:

apache operating principle: when you access an address (send a request), apache starts PHP, then PHP execution is at the page level, that is, if there is executable code: it is all executed before throwing it to apache, apache then throws it to the browser to display the results

How to achieve this?

If the cli displays the results in a different way, what’s the difference?

linux cmd:

php5 test.php

executed directly by php without going through apache or web service, you can achieve:

<?php
  $i = 3;
  while ($i--) {
    echo $i, "\n";
    sleep(1);
  }
  ob_end_clean();
?>

I hope this article will be helpful to everyone’s php programming design.

For more relevant articles on the principle analysis of PHP using ob_flush, which cannot output every second, please pay attention to the PHP Chinese website!