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A comment on Ask HN: What are some cool but obscure data structures you know about?. Parent comment

Re:Ask HN: What are some cool but obscure data structures yo... by polyrand on Friday July 22, 2022 @12:04PM (#32193540)
This is only tangentially related to:

> you avoid computing/fetching the same value twice

But this problem comes up in reverse proxies too. In Nginx, you can set the `proxy_cache_lock`[0] directive to achieve the same effect (avoiding double requests).

[0]: https://nginx.org/en/docs/http/ngx_http_proxy_module.html#pr...

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Re:Ask HN: What are some cool but obscure data structures yo... by talos2110 on Friday July 22, 2022 @12:36PM (#32193953)
That right there is Cache Stampede[0] prevention.

[0]: https://en.wikipedia.org/wiki/Cache_stampede

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Re:Ask HN: What are some cool but obscure data structures yo... by psytrx on Friday July 22, 2022 @02:26PM (#32195437)
Interesting! This is an issue I had with an external API which I intended to cache on my serverless workers infra.

I hit the API's rate limiter when the workers invalidated their cache, even though I staggered the lifetime of the cache keys for each replicated instance. This is how I found out how many Cloudflare workers run on a single edge instance. Hint: It's many.

Didn't know it had a name. I'm delighted, thanks!

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Re:Ask HN: What are some cool but obscure data structures yo... by talos2110 on Friday July 22, 2022 @03:05PM (#32195894)
You’re welcome, happy to help. If you are in the .NET space I suggest you to take a look at FusionCache. It has cache stampede protection built in, plus some other nice features like a fail-safe mechanism and soft/hard timeouts https://github.com/jodydonetti/ZiggyCreatures.FusionCache
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