Upstream Connectivity Availability Tweaks and questions

[daniel.senior]

Having an issue during high traffic will get errors in the log with 502, and
get these errors--"no live upstreams while connecting to upstream"

In my configs it is set to 5 max fails, default of 10s fail time.

1.  Does it try the same session within those 10s--every 2 seconds?  If I
made it 20 seconds would it try every 4 seconds?
2. If another session fails, is it cumulative in that 10s or is it for each
session? 
3. If the server is marked unavailable; what about the current sessions?

4. What would be a better solution?  Extending the fail time? Lessening the
fail time and less attempts?  

Thank you

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,291458,291458#msg-291458