Set up job called twice and fail immediately (race-condition?)
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- Dominant language
- C#
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Description
Describe the bug
When running actions in matrix where resources are far lower than requested count, jobs fail immediately due to set up job step conflicting on the same runner.
We use self-hosted macOS Bare metal machines with one runner per machine.
To Reproduce
- set matrix to run 30 jobs
- set max-parallel to 4
- push to PR and see
Expected behavior
4 actions should run with another 4 following once some complete.
Note: Re-running usually ends up the same on different self hosted runner, and we get stuck on the issue for random amount of time till Github action decide to ... go through,
Runner Version and Platform
2.330.0, macOS 26.2
What's not working?
Runner and Worker's Diagnostic Logs
_diag is empty after the run finishes.
Contributor guide
No contributing guide indexed for this repository
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the issue with a 30-job matrix and max-parallel set to 4 on the reported self-hosted macOS setup, using runner version 2.330.0. Compare the runner behavior and available diagnostics when setup jobs conflict; done means the matrix proceeds in groups of four without immediate failures.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- csharp, github-actions
- Domain
- ci-cd, devops
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100