Output body buffer chain "flattening" doesn't work unless proxy buffering is off

[Maxim Dounin]

Hello!

On Fri, Jun 04, 2010 at 11:56:25PM +0200, Srebrenko Šehić wrote:

> While working on an output body filter, I've noticed that if I flatten
> (join all buffers from a chain into 1 buffer), response processing
> hangs when nginx decides to start buffering the response from the
> upstream server. This usually happens (in my case) when the upstream
> response size is >64k.

You don't marked buffers as send, and proxy has no more free 
buffers to use (proxy_buffers defaults to 8 x 8k == 64k on 
amd64; looks like you didn't tested your code on 32-bit 
platforms... :)).

> If I set "proxy_buffering" to "off" in my
> config, everything works just fine.

This is actually strange.  With proxy_buffering off; it should 
stop doing anything usefull as soon as proxy_buffer_size will be 
exceeded.  Well, it will call output filter again and again, with 
the same buffer chain, but it doesn't seem to match words "works 
just fine".

[...]

Maxim Dounin