proxy_cache_background_update leads to 200 ms delay

Valentin V. Bartenev vbart at
Mon Jul 9 12:16:16 UTC 2018

On Saturday 07 July 2018 08:15:43 stephan13360 wrote:
> Wow, thats it! The delay is gone.
> For now I am satisfied that the delay is gone and will read up some more on
> tcp_nopush.
> For the future: Is there any information on why the combination of
> tcp_nopush and proxy_cache_background_update create the delay and not the
> STALE response you get when the backend ist down and
> proxy_cache_background_update is off?

When a client connection is closing or switching to keepalive state,
the response body left in the socket is explicitly pushed.  In current
implementation the client connection is kept "busy" during background
update and the last chunk may rest in the socket until kernel will send

  wbr, Valentin V. Bartenev

More information about the nginx mailing list