Horizontal Scaling

Deploy multiple worker processes sharing the same database for horizontal scaling. Workers coordinate via database-level locking (FOR UPDATE SKIP LOCKED) — no external coordination required.

// Process A (e.g., machine-1)
const worker = await createInProcessWorker({
  client,
  workerId: "worker-a",
  concurrency: 10,
  processors: { ... },
});

// Process B (e.g., machine-2)
const worker = await createInProcessWorker({
  client,
  workerId: "worker-b",
  concurrency: 10,
  processors: { ... },
});

Each worker needs a unique workerId. Workers compete for available jobs — when one acquires a job, others skip it. The notify adapter (Redis, PostgreSQL LISTEN/NOTIFY, etc.) ensures workers wake up immediately when new jobs are queued.

See examples/state-postgres-multi-worker for a complete example spawning multiple worker processes sharing a PostgreSQL database. See also In-Process Worker reference and State Adapters.