[nginx] Upstream keepalive: keepalive_requests directive.

[Maxim Dounin]

Hello!

On Fri, Aug 10, 2018 at 01:50:04PM -0700, Robert Paprocki wrote:

> Quite the patch. I recall this behavior being discussed a number of times
> in the past.
> 
> Question: why the default of 100? This feels like a significantly breaking
> change wrt. the previous behavior. Are there any plans for advanced
> communication regarding this change, outside of a nominal changelog entry
> (e.g., "introduced 'keepalive_requests' directive")?

The default is 100 to match the same default of the client-side 
keepalive_requests, see http://nginx.org/r/keepalive_requests.  
Also, it is believed that 100 is a good enough number for most 
setups.  While it may be somewhat low for some extreme 
configurations, it can be easily adjusted using the directive.

I don't think that your concerns about "breaking change" are 
relevant, especially keeping in mind that a) upstream keepalive is 
off by default and b) event with upstream keepalive configured, 
requests can easily re-open or close connections for various other 
reasons, in particular - due to limited number of connections 
which are kept in the cache.  Even assuming ideal conditions, 
this change can only affect 1 percent of requests.

-- 
Maxim Dounin
http://mdounin.ru/