proxy_cache_background_update leads to 200 ms delay

[stephan13360]

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?

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,280434,280444#msg-280444