When using php-fpm, fastcgi_finish_request() should be used instead of register_shutdown_function() and exit()
For example, under nginx and php-fpm 5.3+, this will make browsers wait 10 seconds to show output:
<?php
echo "You have to wait 10 seconds to see this.<br>";
register_shutdown_function('shutdown');
exit;
function shutdown(){
sleep(10);
echo "Because exit() doesn't terminate php-fpm calls immediately.<br>";
}
?>
This doesn't:
<?php
echo "You can see this from the browser immediately.<br>";
fastcgi_finish_request();
sleep(10);
echo "You can't see this form the browser.";
?>
