# Task queue

**Source:** https://promtable.com/glossary/task-queue

> A task queue is the backend pattern where work units are submitted to a queue, picked up by workers, and processed asynchronously — Celery, BullMQ, Sidekiq, AWS SQS, Cloud Tasks, Trigger.dev, Inngest are 2026 examples.

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A task queue is the backend pattern where work units are submitted to a queue, picked up by workers, and processed asynchronously — Celery, BullMQ, Sidekiq, AWS SQS, Cloud Tasks, Trigger.dev, Inngest are 2026 examples.

Synchronous request → response works for sub-second work; longer tasks (sending emails, processing images, calling slow LLMs, running batch jobs) need async patterns. Task queues solve this: the web request submits a task, returns immediately, workers process in the background. Implementations: Redis-backed (BullMQ, Sidekiq), Postgres-backed (Hatchet, Graphile Worker), cloud-managed (SQS, Cloud Tasks), full-platform (Trigger.dev, Inngest, Defer). Production gotchas: dead-letter handling for permanently failing tasks, retry strategy (exponential backoff vs immediate retry), task deduplication (idempotency keys), monitoring (queue depth, processing time, failure rate). The right primitive for almost any non-trivial backend work.

## When to use

- Anything that doesn't fit in a single request lifecycle.
- Email, image processing, batch jobs, LLM calls.

## Common mistakes

- No idempotency — retries process the same task twice.
- No dead-letter — failing tasks loop forever.

## Related terms

- [background-job](https://promtable.com/glossary/background-job)
- [durable-execution](https://promtable.com/glossary/durable-execution)
- [workflow-engine](https://promtable.com/glossary/workflow-engine)

*Last updated: 2026-06-01*
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Original page: https://promtable.com/glossary/task-queue
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