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Comment by zcam | Hacker News Reader

If you use it for caching, nginx is lacking something quite important at the moment: stale-while-revalidate (https://tools.ietf.org/html/rfc5861)

Aka serving a cached response while the cache is getting refreshed (even to the request who initiated the refresh). Currently when nginx has to refresh the cache it will "hang" the current response until it gets refreshed (the requests that follow, even while the cache is getting refreshed, will get the stale version tho).

It's the difference between your client being amazed by how fast your api is, to "wtf does page X takes 3s to render from time to time" comments.

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There is an openresty project that provides this https://github.com/pintsized/ledge - also provides ESI and more.

I think "proxy_cache_use_stale updating;" covers this case

Nope: "updating" does what I described, if another request initiated an update and it's in progress, it will serve a stale value, but the request who triggered the update is still "hanging" until the cache is refreshed. So you get that annoying slowdown for at least 1 user (often the CEO of your client company).

The way to work around this issue with nginx (for simple endpoints) is to write scripts that will hit the endpoints to make sure the cache is always hot, but it's a sad, half working hack (the CEO can still hit that cold cache page himself, if lucky enough).

There's a $500 bounty for this [1], but it doesn't look like anyone has taken it on.

[1] - https://www.bountysource.com/issues/972735-proxy_cache_use_s...

The user who posted the bounty has not had any activity on bountysource outside of that bounty as far as I can tell from their profile [0], and it was two years since he and others talked about it in the comments (not including the comment six months ago from someone else since that was not directed at the poster of the bounty). To anyone thinking of fixing the issue, might want to check up on whether the bounty is still up before getting to work. If the bounty is your goal, I mean.

[0]: https://www.bountysource.com/people/23342-bdavis

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