proxy_cache_lock for content revalidation

[Maxim Dounin]

Hello!

On Thu, May 30, 2024 at 01:05:08PM -0700, Maksim Yevmenkin wrote:

> it seems that the proxy_cache_lock directive operates only for cache
> misses (new content). while this behavior is documented, i am curious
> about the reasoning behind it. there are scenarios where
> proxy_cache_lock could be very beneficial for content revalidation.
> what are the community's thoughts on this?

The generic idea is that "proxy_cache_use_stale updating;" is a 
better option for existing cache items.  As such, current 
implementation of proxy_cache_lock doesn't try to handle existing 
cache items to reduce complexity.

Just in case, at least one previous attempt to extend 
proxy_cache_lock to work with existing cache items can be found 
here:

https://mailman.nginx.org/pipermail/nginx-devel/2018-December/011710.html

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