How can I prevent nginx from buffering within PHP? - php

Question

I am trying to push a page to the browser while it is being generated from a PHP script. I have no access to my hosting provider's nginx configuration but they have told me that they use nginx 1.8.1. In my phpinfo() output I can see
output_buffering 0 0
and the same script works as expected on my local PC.
This is my starting script:
<pre>
<?php
for ($i = 0; $i < 100; ++$i) {
print('<b>.</b>');
flush();
usleep(100000); // 0.1 second
}
?>
</pre>
I start getting output immediately on my local PC but I have to wait the full 10 seconds before I see anything when the page is accessed from my hosting.
These are the default response headers:
HTTP/1.1 200 OK
Server: nginx
Date: Tue, 12 Apr 2016 12:32:05 GMT
Content-Type: text/html; charset=UTF-8
Connection: keep-alive
Vary: Accept-Encoding
X-Powered-By: PHP/5.4.45
Content-Encoding: gzip
If I add
<?php
header('X-Accel-Buffering: no');
I get
HTTP/1.1 200 OK
Server: nginx
Date: Tue, 12 Apr 2016 12:35:10 GMT
Content-Type: text/html; charset=UTF-8
Connection: keep-alive
Vary: Accept-Encoding
X-Powered-By: PHP/5.4.45
Content-Encoding: gzip
<?php
header('X-Accel-Buffering: no');
header('Content-Encoding: identity');
HTTP/1.1 200 OK
Server: nginx
Date: Tue, 12 Apr 2016 12:37:11 GMT
Content-Type: text/html; charset=UTF-8
Content-Length: 812
Connection: keep-alive
X-Powered-By: PHP/5.4.45
Content-Encoding: identity
Obviously, if the server knows the length of the content, it has waited for the script to finish before starting to send it to the browser.
These are the headers on my local machine:
HTTP/1.1 200 OK
Date: Tue, 12 Apr 2016 12:52:31 GMT
Server: Apache/2.4.7 (Win32) PHP/5.4.45 OpenSSL/1.0.1e
X-Powered-By: PHP/5.4.45
X-Accel-Buffering: no
Content-Encoding: identity
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=utf-8
The X-Accel-Buffering header gets passed through because I am not running nginx locally.
Are there any other headers I can pass through from PHP to stop nginx from buffering the content? So far I've only found config options, which I don't have access to.