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By default every worker serves every project from one shared queue. When one busy project floods it, everyone else waits. Worker groups fix that. A group is a named pool of workers with its own dedicated queue. Assign a project to a group and its runs get reserved workers no other project can take. Worker groups: projects map to dedicated queues, each backed by its own reserved worker pool, while ungrouped projects share a best-effort queue

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Floor vs. ceiling

  • A worker group is a floor: capacity reserved for a project that nobody else can use.
  • A soft cap is a ceiling: an optional per-project limit on how much a project can use. See Manage Concurrency for details.
Use both together to guarantee capacity for busy projects and cap the rest.

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How it works

A worker joins a group by setting its group ID at startup. AP_PROJECT_WORKER selects the group’s scope:
  • Project group — leave AP_PROJECT_WORKER=true (the default). Assign individual projects to it from the platform’s Workers → Assignments page.
  • Platform group — set AP_PROJECT_WORKER=false. Serves the whole platform’s runs; used for dedicated/canary fleets.
Grouped workers run in a process-isolated execution mode, so set:
Routing runs to worker group queues is done by the project rate limiter, so the app server must run with AP_PROJECT_RATE_LIMITER_ENABLED=true. Without it, assigned projects keep using the shared queue and grouped workers stay idle.
Once a project is assigned to a group, its flow and webhook runs are routed to that group’s dedicated queue (project-<group-name>-jobs) and picked up only by workers carrying the matching AP_WORKER_GROUP_ID with AP_PROJECT_WORKER=true. Projects without a group keep drawing from the shared queue.

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Assigning projects to a group

You can assign a project to a project group in two ways:
  • UI — go to Platform → Infrastructure → Workers (/platform/infrastructure/workers), open the Assignments tab, and pick the group for each project.
  • API — set workerGroupId on the project via the projects API. Use the bare group name (the same value as the group’s AP_WORKER_GROUP_ID); pass null to unassign and return the project to the shared queue.
The same request also sets maxConcurrentJobs — the project’s concurrency limit (the soft-cap ceiling). It’s the maximum number of flow runs the project executes at once:
  • Omit it (or send null) and the project uses the default: min(plan limit, group slots) — i.e. it can use the group’s full reserved capacity, up to the plan’s limit.
  • Set a number to cap the project below that. The value is clamped to the group’s slot count (a project can’t run more concurrently than its pool can serve).