Reduce API docs generation time by 97%

[ironcladlou]

Optimize the API docs generation by disabling the use of Go modules
when running the generation tool. This is a workaround for performance
issues in the upstream libraries:

• Use x/tools/go/packages kubernetes/gengo#147
• performance drop with GO111MODULE="on" kubernetes/code-generator#69

Before this workaround:

make api-docs  93.87s user 171.98s system 426% cpu 1:02.30 total

After the workaround:

make api-docs  2.91s user 0.83s system 135% cpu 2.752 total

The hack seems worth the 97% improvement for iterating on docs.

[openshift-ci]

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[enxebre]

Which version of go are you using?
What would be the impact if we only to set GO111MODULE="off"? why is the fake go path needed?
FWIW Seems like the reporter managed to reduce performance penalty without the script kubernetes/code-generator#69 (comment)

/lgtm
/hold
To answer my questions above, otherwise feel free to cancel the hold.

[ironcladlou]

Which version of go are you using?

1.16

What would be the impact if we only to set GO111MODULE="off"?

The tool doesn't work because we're outside GOPATH.

why is the fake go path needed?

Because the performance issues only manifest when running with GO111MODULE=on, and if you set GO111MODULE=off, the code needs to be in GOPATH, which nothing in our current tooling assumes (correctly). If I've got it wrong and there's another way please let me know and I'll refactor.

FWIW Seems like the reporter managed to reduce performance penalty without the script kubernetes/code-generator#69 (comment)

None of the changes they mention include fixing the tool. What exactly did the commenter change that would be applicable here? Nowhere in their explanation do I see any mention of fixing code-generator or gen-crd-api-reference-docs themselves.

/lgtm /hold To answer my questions above, otherwise feel free to cancel the hold.

I don't see any alternative being proposed and the current performance is unacceptable. We can always just remove the hack if somebody comes up with a better way.

[ironcladlou]

/hold cancel