fix(core): drain stdout before exit in print-affected

[forivall]

Piping a large print-affected output to another command, such as cat or jq, resulted in broken json output as the node process can exit before the output is fully written. The process.stdout stream needs to wait to drain before process.exit.

Current Behavior

Sometimes, when I pipe nx print-affected --all to another command, such as cat or jq, the output will be truncated. For example:

~pubrepos/nx forivall/print-affected-stdout-drain ≡
» nx print-affected --all | cat
{
  "tasks": [],
  "projects": [
    "nx-dev-feature-package-schema-viewer",
    "make-angular-cli-faster",
...
          "type": "static"
        }
      ],
      "nest": [
        {
          "source": "nest",
          "target": "node",
          "type": "impli
~pubrepos/nx forivall/print-affected-stdout-drain ≡
» nx print-affected --all | jq .
parse error: Unfinished JSON term at EOF at line 3479, column 3

Expected Behavior

» nx print-affected --all | jq .
{
  "tasks": [],
  "projects": [
    "nx-dev-feature-package-schema-viewer",
    "make-angular-cli-faster",
    "create-nx-workspace",
...

Related Issue(s)

I don't think this issue has been reported yet.

Fixes #

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✅ Successfully ran 12 targets

• nx affected --target=e2e --base=8ab7f85ca13df2e6d37f69f1bebe6ed5f00c3899 --head=31ecffa354c13d2e3fee5431ae6716278e66d205 --exclude=e2e-storybook,e2e-storybook-angular,e2e-react-native,e2e-detox,e2e-make-angular-cli-faster --parallel=1
• nx affected --target=test --base=8ab7f85ca13df2e6d37f69f1bebe6ed5f00c3899 --head=31ecffa354c13d2e3fee5431ae6716278e66d205 --parallel=1
• nx affected --target=build --base=8ab7f85ca13df2e6d37f69f1bebe6ed5f00c3899 --head=31ecffa354c13d2e3fee5431ae6716278e66d205 --parallel=3
• nx-cloud record -- yarn depcheck
• nx affected --target=lint --base=8ab7f85ca13df2e6d37f69f1bebe6ed5f00c3899 --head=31ecffa354c13d2e3fee5431ae6716278e66d205 --parallel=3
• nx-cloud record -- yarn nx workspace-lint
• nx-cloud record -- yarn check-lock-files
• nx-cloud record -- yarn check-commit
• nx-cloud record -- yarn nx format:check --base=8ab7f85ca13df2e6d37f69f1bebe6ed5f00c3899 --head=31ecffa354c13d2e3fee5431ae6716278e66d205
• nx-cloud record -- yarn check-imports
• nx-cloud record -- yarn documentation
• nx build typedoc-theme

---

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[forivall]

alternative:

Suggested change

	if (process.stdout.writableNeedDrain) {
	process.stdout.once('drain', resolve);
	} else {
	resolve();
	}
	process.stdout.write('', resolve);

Notably, writableNeedDrain was added in node 14.17.0, so on earlier node versions, the code that checks writableNeedDrain won't wait for drain; that is the current behaviour, so that's somewhat moot.

[github-actions]

This pull request has already been merged/closed. If you experience issues related to these changes, please open a new issue referencing this pull request.