Arbiter

A PostgreSQL job queue for Haskell applications.

• Transactional job processing: jobs and database operations commit together
• At-least-once delivery with leases and heartbeats
• Per-group ordering (partitioned FIFO)
• Concurrent worker pools with LISTEN/NOTIFY wakeups and polling fallback
• Dead-letter queues
• Opt-in archiving of completed jobs with per-job retention
• Job trees with fan-out/fan-in result collection
• Cron/periodic job scheduling
• Job deduplication via unique keys
• Cross-queue per-job rate limiting with operator-tunable token-bucket policies
• Cross-queue per-job concurrency limits: at most N jobs with the same key can be in flight
• Integrated OpenTelemetry traces, with metrics and logs from arbiter-otel
• Observability callbacks, structured logging
• REST API with SSE and an embedded admin UI
• File-based liveness probes for Kubernetes and systemd