Fan-Out / Fan-In - CI/CD Glossary Definition
Fan-out / fan-in is a pipeline pattern where one stage splits work into many parallel jobs (fan-out), and a later stage waits for all of them to finish before aggregating their results (fan-in). It is how CI parallelizes test suites and then collects the verdict.
In GitHub Actions
Fan-out is a matrix or multiple independent jobs; fan-in is a final job that lists every parallel job under needs:, so it only runs once they all succeed.
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