perf: patch libuv to use posix_spawn on macOS

[pdesantis]

Description of Change

Spawning child processes in an Electron application with a hardened runtime has become slow in macOS Big Sur.

This patch is a squashed version of libuv/libuv#3064, and should be removed when the libuv PR is merged.

Fixes: libuv/libuv#3050
Fixes: #26143
PR-URL: libuv/libuv#3064

Special thanks

@jpcanepa: authoring the libuv patch
@davidzech @marcello3d @srubin: identifying the underlying Electron issue
@marcello3d: creating the Electron repro
@bnoordhuis: assistance with libuv

Stakeholders

@deepak1556: thanks for the libuv repro
@erickzhao: thanks for the support in the Electron Discord & assisting with Electron build-tools

Checklist

• PR description included and stakeholders cc'd
• PATH env var breaking change is fixed
• npm test passes
• tests are changed or added
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixed slow child process spawning on macOS Big Sur

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[nornagon]

Am I correct in understanding that the breaking change is that previously, the PATH in the env option was used to resolve the executable, but now the PATH of the parent process is used? That seems potentially dangerous, but I'll leave that to the libuv maintainers to comment on. We should hold on merging this until we clarify whether we feel OK about merging that breaking change or if there's a way to restore the old behavior and make this non-breaking.

[pdesantis]

@nornagon thanks for taking a look! Correct, that's the breaking change I was referring to (I'll update the description to clarify). In my opinion this should not be merged until that is fixed. My motivations for the draft PR are:

1. This has fixed the Big Sur issue for us, hopefully some others in the community find it useful.
2. Once the blocker is resolved, is this the correct way to patch Electron?

[nornagon]

@pdesantis yes, this is the right way to land a patch in Electron.

[codebytere]

@pdesantis do you still plan to work on this?

[pdesantis]

@codebytere yes! I'm just waiting on final approval for libuv/libuv#3064 (which we submitted yesterday), then will update this PR.

[pdesantis]

@codebytere @nornagon I'm marking this as Ready for Review now. We fixed the aforementioned breaking change and have received 1 merge approval on libuv PR libuv/libuv#3064 (but it has not been merged yet).

I'm guessing you want to wait for libuv to merge the PR, but figured now is a good time to start the Electron review process.

I had to make 1 change to the patch (stripping trailing whitespace) to pass Electron's lint. I can squash this down into 1 commit once the review is done.

[nornagon]

I'm OK merging / backporting this once it's merged upstream.

[pdesantis]

I'm OK merging / backporting this once it's merged upstream.

Awesome, I'll report back once it's merged. In the meantime, what should I do about these test failures?

[jkleinsc]

@pdesantis the patch needs to be updated. If you are using electron build tools, you can run e patches node on your local checkout which should update the patch locally. Alternatively, you can go to one of the failed jobs, eg https://app.circleci.com/pipelines/github/electron/electron/35194/workflows/fe990252-b819-4d60-91ce-833802f7b2ee/jobs/771654, click on the Artifacts tab, and download the file patches/update-patches.patch to your electron dir and then run git am update-patches.patch

[andrejgloot]

libuv/libuv#3064 PR has been merged and closed now

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[release-clerk]

Release Notes Persisted

Fixed slow child process spawning on macOS Big Sur

[trop]

I have automatically backported this PR to "11-x-y", please check out #27654

[trop]

I have automatically backported this PR to "10-x-y", please check out #27655

[trop]

I have automatically backported this PR to "12-x-y", please check out #27656