Background Jobs Agent Skill

---
description: Queue workers with BullMQ/Inngest/Trigger.dev, job retries, dead letter queues, concurrency.
homepage: https://yepapi.com/skills/background-jobs
metadata:
  tags: [queues, jobs, bullmq, inngest]
---

# Background Jobs

## Rules

- Offload slow work to background jobs: emails, image processing, webhooks, reports, AI calls
- BullMQ for self-hosted Redis queues — Inngest or Trigger.dev for serverless/managed
- Every job must be idempotent — safe to retry without side effects (use idempotency keys)
- Retry with exponential backoff: 3-5 attempts, delays of 1s, 10s, 60s, 5min
- Dead letter queue (DLQ): after max retries, move to DLQ for investigation — never silently drop
- Set concurrency limits per queue — prevent worker overload (e.g., `concurrency: 5`)
- Job payloads should be small: pass IDs and references, not full objects
- Separate queues by priority: `critical` (payments), `default` (emails), `low` (analytics)
- Monitor queue depth and processing time — alert when queue backs up

## Patterns

```ts
// BullMQ pattern
import { Queue, Worker } from "bullmq";
const queue = new Queue("emails", { connection: redis });

await queue.add("welcome", { userId }, {
  attempts: 3,
  backoff: { type: "exponential", delay: 1000 },
});

const worker = new Worker("emails", async (job) => {
  await sendWelcomeEmail(job.data.userId);
}, { connection: redis, concurrency: 5 });
```

```ts
// Inngest serverless pattern
import { inngest } from "./client";

export const sendEmail = inngest.createFunction(
  { id: "send-welcome-email", retries: 3 },
  { event: "user/created" },
  async ({ event }) => { await sendWelcomeEmail(event.data.userId); }
);
```

## Avoid

- Processing slow tasks in API request handlers — respond fast, process in background
- Non-idempotent jobs — duplicate execution will cause double charges, double emails
- Unbounded concurrency — will exhaust database connections and memory
- Storing large payloads in the job queue — pass references instead