Build Queues

Build queueing is when a build must wait for resources to become available before starting. This creates more time between when the code is committed and the deployment being ready.

• With On-Demand Concurrent Builds, builds will never queue.
• Without On-Demand Concurrent Builds, builds can queue under the conditions specified below.

On-Demand Concurrent Builds prevent all build queueing so your team can build faster. Your builds will never be queued becuase Vercel will dynamically scale the amount of builds that can run simultaneously.

If you're experiencing build queues, we strongly recommend enabling On-Demand Concurrent Builds. For billing information, visit the usage and limits section for builds.

When multiple deployments are started concurrently from code changes, Vercel's build system places deployments into one of the following queues:

• Concurrency queue: The basics of build resource management
• Git branch queue: How builds to the same branch are managed

This queue manages how many builds can run in parallel based on the number of concurrent build slots available to the team. If all concurrent build slots are in use, new builds are queued until a slot becomes available unless you have On-Demand Concurrent Builds enabled at the project level.

Concurrent build slots are the key factor in concurrent build queuing. They control how many builds can run at the same time and ensure efficient use of resources while prioritizing the latest changes.

Each account plan comes with a predefined number of build slots:

• Hobby accounts allow one build at a time.
• Pro accounts support up to 12 simultaneous builds.
• Enterprise accounts can have custom limits based on their plan.

Builds are handled sequentially. If new commits are pushed while a build is in progress:

1. The current build is completed first.
2. Queued builds for earlier commits are skipped.
3. The most recent commit is built and deployed.

This means that commits in between the current build and most recent commit will not produce builds.