Concurrency Group - CI/CD Glossary Definition

A concurrency group is the key that decides which runs contend for the same concurrency slot.

A concurrency group is the string key under concurrency.group that identifies which runs contend for the same concurrency slot; runs sharing a group cannot run at the same time.

The group expression, often built from the workflow name and ref, buckets runs. Only one run per group is active; newer runs queue or cancel older ones depending on cancel-in-progress.

Choosing a key

A per-branch key (${{ github.ref }}) serializes runs of the same branch while letting different branches run in parallel. A global constant serializes everything, which is rarely desirable.

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