php server side events [sse]

[Maxim Dounin]

Hello!

On Wed, Aug 26, 2015 at 12:33:48PM -0700, dmiller at amfes.com wrote:

> I have several virtual servers operating with php-fpm perfectly fine.
> Buffering/caching with Wordpress is great.  But now...
> 
> I'm trying to implement a new site that uses php for server-side events to
> stream live updates to clients.  This is, I believe, properly done with an
> infinite loop in php that will send events as they occur.  The problem is
> the events seem to be getting buffered and don't appear.
> 
> If I write the php program to end after sending an event then it works.  If
> I restart php-fpm then it works - at least for a while.
> 
> I've tried numerous config options - obviously what I'm trying isn't
> working.  Any suggestions?

By default, nginx only starts sending data to a client once it has 
a full buffer ready.  If you want to stream data immediately, 
you have to switch off buffering - either with the fastcgi_buffering 
directive, or using the X-Accel-Buffering header in a response.  
See http://nginx.org/r/fastcgi_buffering for details.

Additionally, there are some buffering option in PHP.  I'm not a 
PHP expert, but likely flush() function will help if the problem 
is on PHP side, see http://php.net/manual/en/function.flush.php.

-- 
Maxim Dounin
http://nginx.org/