feat(env): auto set GOMAXPROCS

[dongjiang1989]

Description

Auto set GOMAXPROCS.
add dependency on go.uber.org/automaxprocs

Checklist

• Unit tests updated
• End user documentation updated

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @dongjiang1989. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[dongjiang1989]

/ok-to-test

[k8s-ci-robot]

@dongjiang1989: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

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[dongjiang1989]

@mloiseleur PTAL

[mloiseleur]

I have mixed feeling with this PR.
This kind of optimization should be done by either the language or the admin.

[dongjiang1989]

I have mixed feeling with this PR. This kind of optimization should be done by either the language or the admin.

Thanks for your review. @mloiseleur
The containers to pick up the correct GOMAXPROCS based on the CPU resource limits.
ref: https://pkg.go.dev/go.uber.org/automaxprocs?utm_source=godoc

[szuecs]

@dongjiang1989 what do you try to fix?
I don't see why we should add a dependency for a thing that is not important for control loops like external-dns.

[dongjiang1989]

@dongjiang1989 what do you try to fix? I don't see why we should add a dependency for a thing that is not important for control loops like external-dns.

As you all know node/pod come with different sizes. For example, we use quite huge nodes with up to 104 CPUs, we aren't able to set environment variables to set GOMAXPROCS to the value of cpu.limit. automaxprocs package does this automatically without any additional pain. If there are not limits specified, default value (number of cores) will be left in place.

[mloiseleur]

we aren't able to set environment variables to set GOMAXPROCS to the value of cpu.limit

IMHO, this is the problem you should solve on your platform, not with external-dns source code.. You may also be interested to tune GOMEMLIMIT.