Implement closing stdin for graceful process termination

[mehrdadn]

Why are these changes needed?

Uses stdin closure to signal process termination to children.

Checks

• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/latest/.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failure rates at https://ray-travis-tracker.herokuapp.com/.
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested (please justify below)

[AmplabJenkins]

Can one of the admins verify this patch?

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/29271/
Test FAILed.

[bveeramani]

‼️ ACTION REQUIRED ‼️

We've switched our code formatter from YAPF to Black (see #21311).

To prevent issues with merging your code, here's what you'll need to do:

1. Install Black

pip install -I black==21.12b0

2. Format changed files with Black

curl -o format-changed.sh https://gist.githubusercontent.com/bveeramani/42ef0e9e387b755a8a735b084af976f2/raw/7631276790765d555c423b8db2b679fd957b984a/format-changed.sh
chmod +x ./format-changed.sh
./format-changed.sh
rm format-changed.sh

3. Commit your changes.

git add --all
git commit -m "Format Python code with Black"

4. Merge master into your branch.

git pull upstream master

5. Resolve merge conflicts (if necessary).

After running these steps, you'll have the updated format.sh.

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

• If you'd like to keep this open, just leave any comment, and the stale label will be removed.

[kfstorm]

‼️ ACTION REQUIRED ‼️

We've updated our formatting configuration for C++ code. (see #22725)

This PR includes C++ code change. To prevent issues with merging your code, here's what you'll need to do:

1. Merge the latest changes from upstream/master branch into your branch.

git pull upstream master
git merge upstream/master

2. Resolve merge conflicts (if necessary).

After running these steps, you'll have the updated C++ formatting configuration.

3. Format changed files.

scripts/format.sh

4. Commit your changes.

git add --all
git commit -m "Format C++ code"

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

• If you'd like to keep this open, just leave any comment, and the stale label will be removed.

[stale]

Hi again! The issue will be closed because there has been no more activity in the 14 days since the last message.

Please feel free to reopen or open a new issue if you'd still like it to be addressed.

Again, you can always ask for help on our discussion forum or Ray's public slack channel.

Thanks again for opening the issue!