Spawned child process not killed on GitHub Actions

[karlhorky]

What version of Bun is running?

1.1.13+bd6a60512

What platform is your computer?

Darwin 23.5.0 arm64 arm

What steps can reproduce the bug?

1. Create a GitHub Actions workflow with a Bun script index.ts
2. In index.ts, create a yarn run dev child process with spawn() and use .kill() on that child process
3. Observe that the child process is still running

Reproduction repo with GitHub Actions workflow:

• repo: https://github.com/karlhorky/repro-bun-spawn-kill-fails-on-github-actions
• failing GitHub Actions workflow run: https://github.com/karlhorky/repro-bun-spawn-kill-fails-on-github-actions/actions/runs/9529302546/job/26267905138

What is the expected behavior?

childProcess.kill() kills process instantly on GitHub Actions

Locally, this works:

$ bun index.ts
1718467629038 childProcess1 started with PID 32286
1718467629046 Sleeping for 2 seconds...
1718467630077 childProcess1 exited with exit code 1
1718467630077 Waiting for stdoutPromise to resolve (hangs on CI)...
1718467630077 childProcess2 started with PID 32293
1718467630078 childProcess2 exited with exit code 143

What do you see instead?

childProcess.kill() does not kill the process on GitHub Actions

On GitHub Actions, it hangs on waiting for the promise

$ bun index.ts
1718467554080 childProcess1 started with PID 1828
1718467554083 Sleeping for 2 seconds...
1718467555094 childProcess1 exited with exit code 1
1718467555094 Waiting for stdoutPromise to resolve (hangs on CI)...
Error: The action 'Run script' has timed out after 1 minutes.

Additional information

I found some issues which relate to some of the same things over here:

• process.kill(constants.signals.SIGINT) not working as expected #2092
• Killing a subprocess while .read()ing a buffered stdout causes bun to remain open. #1498

Also, some discussion about how GitHub Actions terminates child processes differently:

• https://github.com/orgs/community/discussions/26311#discussioncomment-6237346

[karlhorky]

Workaround 1

Through some trial and error, I found that running killall node causes the process to finish and the stdout to be read:

+import { $ } from 'bun';

// ...

-childProcess1.kill();
+await $`killall node`;

I also used this as a workaround before, to avoid the Cypress action not shutting down a dev server:

• Does the server started with the start parameter shut down at the end? cypress-io/github-action#360 (comment)

[karlhorky]

Workaround 2

Changing the packageManager field in package.json to [email protected] also seems to work around the issue:

{
-  "packageManager": "[email protected]+sha512.a6b2f7906b721bba3d67d4aff083df04dad64c399707841b7acf00f6b133b7ac24255f2652fa22ae3534329dc6180534e98d17432037ff6fd140556e2bb3137e"
+  "packageManager": "[email protected]"
}

Successful workflow run: https://github.com/karlhorky/repro-bun-spawn-kill-fails-on-github-actions/actions/runs/9529280612

It fails with either packageManager set to yarn@<version> or no packageManager field in package.json

Maybe this is related to Corepack on GitHub Actions?

[karlhorky]

The longer I look at this issue, the less it looks directly related to Bun.

But it would be nice for Bun to have identical behavior with spawning + killing child processes on a local machine and GitHub Actions... 🤔