{
    "api": "YAML JSON TOON Database",
    "version": "1.0.0",
    "format": "json",
    "dataset": {
        "id": 1016,
        "slug": "reliable-background-jobs",
        "title": "Reliable Background Job Patterns",
        "description": "Queue and worker design patterns for duplicate deliveries, failure recovery, concurrency, and bounded work.",
        "summary": "Queue and worker design patterns for duplicate deliveries, failure recovery, concurrency, and bounded work. Each row includes a practical application and a failure to check before using it.",
        "use_when": [
            "Design a worker that can safely retry after a crash.",
            "Separate delivery guarantees from business effects."
        ],
        "caveats": [
            "Exactly-once delivery claims do not establish exactly-once external effects.",
            "Patterns must be implemented with the database and queue’s real atomicity guarantees."
        ],
        "related": [
            "observability-signals",
            "concurrency-design-patterns"
        ],
        "category": "Design Patterns",
        "category_slug": "design-patterns",
        "tags": "design-patterns,reliable background jobs,reference,engineering",
        "view_count": 0,
        "created_at": 1791798640,
        "updated_at": 1791798640,
        "reviewed_at": "2026-10-12",
        "sources": [
            {
                "title": "AWS SQS delivery semantics",
                "url": "https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/standard-queues-at-least-once-delivery.html"
            },
            {
                "title": "AWS transactional outbox pattern",
                "url": "https://docs.aws.amazon.com/prescriptive-guidance/latest/cloud-design-patterns/transactional-outbox.html"
            }
        ],
        "reading": [
            "background-jobs-idempotency-and-the-outbox-pattern"
        ],
        "provenance": "Original editorial reference notes by YJTOON, informed by the linked primary documentation. External specifications retain their own licenses.",
        "entry_count": 10,
        "fields": [
            {
                "section": "data",
                "field": "pattern",
                "type": "string",
                "example": "Idempotent handler"
            },
            {
                "section": "data",
                "field": "mechanism",
                "type": "string",
                "example": "Make repeated application produce the intended …"
            },
            {
                "section": "data",
                "field": "use",
                "type": "string",
                "example": "Handle at-least-once message delivery."
            },
            {
                "section": "data",
                "field": "failure_to_test",
                "type": "string",
                "example": "Deliver the same job twice."
            }
        ]
    },
    "data": [
        {
            "pattern": "Idempotent handler",
            "mechanism": "Make repeated application produce the intended single result.",
            "use": "Handle at-least-once message delivery.",
            "failure_to_test": "Deliver the same job twice."
        },
        {
            "pattern": "Deduplication key",
            "mechanism": "Persist a stable key with the committed effect.",
            "use": "Prevent repeating one business operation.",
            "failure_to_test": "Crash between recording the key and committing the effect."
        },
        {
            "pattern": "Transactional outbox",
            "mechanism": "Commit the domain change and outgoing record together.",
            "use": "Keep a database write aligned with event publication.",
            "failure_to_test": "Crash after commit but before publication."
        },
        {
            "pattern": "Visibility timeout",
            "mechanism": "Lease a job for a bounded processing interval.",
            "use": "Recover work from a failed worker.",
            "failure_to_test": "Run a job longer than the lease."
        },
        {
            "pattern": "Lease heartbeat",
            "mechanism": "Extend a lease while an owned job is progressing.",
            "use": "Support long-running bounded tasks.",
            "failure_to_test": "Lose connectivity during an extension."
        },
        {
            "pattern": "Exponential backoff",
            "mechanism": "Increase delay between repeated failures with jitter.",
            "use": "Reduce pressure on a failing dependency.",
            "failure_to_test": "Make many workers fail simultaneously."
        },
        {
            "pattern": "Dead-letter queue",
            "mechanism": "Move repeatedly failing jobs aside with evidence.",
            "use": "Keep a poison job from blocking useful work.",
            "failure_to_test": "Replay a corrected job without duplicating effects."
        },
        {
            "pattern": "Concurrency limit",
            "mechanism": "Bound active jobs per resource or tenant.",
            "use": "Protect downstream capacity.",
            "failure_to_test": "Enqueue a burst above steady-state throughput."
        },
        {
            "pattern": "Cancellation",
            "mechanism": "Check a cooperative cancellation signal at safe points.",
            "use": "Stop obsolete or user-cancelled work.",
            "failure_to_test": "Cancel while an external side effect is in flight."
        },
        {
            "pattern": "Checkpoint",
            "mechanism": "Persist completed progress under a versioned contract.",
            "use": "Resume a long task after a crash.",
            "failure_to_test": "Resume with a changed code or data version."
        }
    ]
}