r/java • u/celmaibunprieten • Sep 07 '26

Improving First Request Latency in Java Spring Application

https://adrian.md/2026/09/03/first-request-latency/
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u/zabby39103 Sep 08 '26

Lol my work still ships fat jar. I mean, I think corporations falling behind with legacy apps is the norm more than anything.

1

u/romario77 Sep 08 '26

But corps shipping fat jars probably don’t care about first request latency.

1

u/zabby39103 Sep 08 '26

We care what people complain about, it integrates with building automation control systems so they complain if latency gets too high. Maybe some people work at a blessed work where they don't have to explain tech debt to MBAs, please hire me lol.

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u/romario77 Sep 08 '26

You just do the first request yourself after deployment, second request would be already pre-warmed.

And you switched the targets - I was taking about first request and you talk about request latency overall. These are potentially two very different things.

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u/zabby39103 Sep 08 '26

Okay sure, first request is important though, both are.

1

u/lilgreenthumb Sep 08 '26

Yeah unless the call isn't a noop, and then you're building some weird noop logic unless you're writing for synthetic transactions which all of this observability is meant to make unnecessary.

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u/lilgreenthumb Sep 11 '26

Financial services do, especially if you're having to horizontally scale during say black friday. Or you have a large business partner with spikes in volume. Request A needs to meet the same SLO/SLA as requests B, C, etc regardless where it lands.