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Comment by yencabulator | Hacker News Reader

This should be automatic these days (for the basic scenarios).

https://github.com/golang/go/blob/a1a151496503cafa5e4c672e0e...

This is probably going to save quadrillions of CPU cycles by making an untold number of deployed Go applications a bit more CPU efficient. Since Go is the "lingua franca" of containers, many ops people assume the Go runtime is container-aware - it's not (well not in any released version, yet).

If they'd now also make the GC respect memory cgroup limits (i.e. automatic GOMEMLIMIT), we'd probably be freeing up a couple petabytes of memory across the globe.

Java has been doing these things for a while, even OpenJDK 8 has had those patches since probably before covid.

GOMEMLIMIT is not as easy, you may have other processes in the same container/cgroup also using memory.

As long as I admit respecting cgroup's setting is a good thing, I am not sure it's really quadrillions.

Or is it? Need calculations

I would've expected it to be either way too much or way too little, but after doing the math it could be sorta in the right ballpark, at least cosmically speaking.

Let's go with three quadrillion (which is apparently 10^15), let's assume a server CPU does 3 GHz (10^9), that's 10^6, a day is about 100k seconds, so ~ten days. But of course we're only saving cycles. I've seen throughput increase by about 50% when setting GOMAXPROCS on bigger machines, but in most of those cases we're looking at containers with fractional cores. On the other hand, there are many containers. So...

Nice reasoning, thanks.

Hey, but what did you have in mind with regard to bigger machines? I think we're talking here about lowering GOMAXPROCS to have in effect less context switching of the OS threads. While it can bring some good result, a gut feeling is that it'd be hardly 50% faster overall, is your scenario the same then?

uh isn't that change 3 hours old?

Oh heh yes it is. I just remembered the original discussion from 2019 (https://github.com/golang/go/issues/33803) and grepped the source tree for cgroup to see if that got done or not, but didn't check when it got done.

As said in 2019, import https://github.com/uber-go/automaxprocs to get the functionality ASAP.

super-weird coincidence but welcome, I have been waiting for this for a long time!

I honestly can’t count on my fingers and toes how many times something very precisely relevant to me was brought up or sorted out hours-to-days before I looked it up. And more often than once, by people I personally knew!

Always a weird feeling, it’s a small world

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