output_buffers value breaks thread_pool/aio on 1.9.5+

[Valentin V. Bartenev]

On Sunday 06 December 2015 01:28:15 Richard Kearsley wrote:
> Hi
> Since 1.9.5,
> *) Change: now the "output_buffers" directive uses two buffers by default.
> 
> The two buffers do not work with thread_pool/aio, the connection is 
> closed at 32,768 bytes (size of one buffer)

I've just tested and everything worked fine.
It seems there are other factors.

> 
> These messages are shown in the error log:
> [alert] 126931#126931: task #106 already active
> 
> - Changing output_buffers back to 1 32k avoids the problem
> - aio=off avoids the problem
> 

Could you provide full configuration and a debug log?
http://nginx.org/en/docs/debugging_log.html

  wbr, Valentin V. Bartenev