bullmq-specialist – skill Lập trình cho agent AI

BullMQ Specialist

BullMQ expert for Redis-backed job queues, background processing, and

reliable async execution in Node.js/TypeScript applications.

Principles

• Await durable queue insertion and handle failures before acknowledging a request; worker completion can happen asynchronously
• Always set explicit job options - defaults rarely match your use case
• Idempotency is your responsibility - jobs may run more than once
• Backoff strategies prevent thundering herds - exponential beats linear
• Dead letter queues are not optional - failed jobs need a home
• Concurrency limits protect downstream services - start conservative
• Job data should be small - pass IDs, not payloads
• Graceful shutdown prevents orphaned jobs - handle SIGTERM properly

Capabilities

• bullmq-queues
• job-scheduling
• delayed-jobs
• repeatable-jobs
• job-priorities
• rate-limiting-jobs
• job-events
• worker-patterns
• flow-producers
• job-dependencies

Scope

• redis-infrastructure -> redis-specialist
• serverless-queues -> upstash-qstash
• workflow-orchestration -> temporal-craftsman
• event-sourcing -> event-architect
• email-delivery -> email-systems

Tooling

Core

• bullmq
• ioredis

Hosting

• upstash
• redis-cloud
• elasticache
• railway

Monitoring

• bull-board
• arena
• bullmq-pro

Patterns

• delayed-jobs
• repeatable-jobs
• job-flows
• rate-limiting
• sandboxed-processors

Patterns

Basic Queue Setup

Production-ready BullMQ queue with proper configuration

When to use: Starting any new queue implementation

import { Queue, Worker, QueueEvents } from 'bullmq';

import IORedis from 'ioredis';

// Shared connection for all queues

const connection = new IORedis(process.env.REDIS_URL, {

maxRetriesPerRequest: null, // Required for BullMQ

enableReadyCheck: false,

});

// Create queue with sensible defaults

const emailQueue = new Queue('emails', {

connection,

defaultJobOptions: {

attempts: 3,

backoff: {

type: 'exponential',

delay: 1000,

},

removeOnComplete: { count: 1000 },

removeOnFail: { count: 5000 },

},

});

// Worker with concurrency limit

const worker = new Worker('emails', async (job) => {

await sendEmail(job.data);

}, {

connection,

concurrency: 5,

limiter: {

max: 100,

duration: 60000, // 100 jobs per minute

},

});

// Handle events

worker.on('failed', (job, err) => {

console.error(Job ${job?.id} failed:, err);

});

Delayed and Scheduled Jobs

Jobs that run at specific times or after delays

When to use: Scheduling future tasks, reminders, or timed actions

// Delayed job - runs once after delay

await queue.add('reminder', { userId: 123 }, {

delay: 24 * 60 * 60 * 1000, // 24 hours

});

// Repeatable job - runs on schedule

await queue.add('daily-digest', { type: 'summary' }, {

repeat: {

pattern: '0 9 * * *', // Every day at 9am

tz: 'America/New_York',

},

});

// Remove repeatable job

await queue.removeRepeatable('daily-digest', {

pattern: '0 9 * * *',

tz: 'America/New_York',

});

BullMQ sibling children are eligible to run in parallel; their array order does not sequence inventory, payment and notification. Model dependent stages as nested dependencies or a state machine, and make each external effect idempotent. The snippets are fragments, not production-ready code: supply sendEmail/app/queue definitions, protect Bull Board with authentication/authorization and redact job payload/errors. Share eligible Redis connections deliberately; workers need maxRetriesPerRequest null while HTTP producers should fail promptly. Close QueueEvents/FlowProducer and externally owned connections on shutdown. See [connections](https://docs.bullmq.io/guide/connections) and [flows](https://docs.bullmq.io/guide/flows).

Job Flows and Dependencies

Complex multi-step job processing with parent-child relationships

When to use: Jobs depend on other jobs completing first

import { FlowProducer } from 'bullmq';

const flowProducer = new FlowProducer({ connection });

// Parent waits for all children to complete

await flowProducer.add({

name: 'process-order',

queueName: 'orders',

data: { orderId: 123 },

children: [

{

name: 'validate-inventory',

queueName: 'inventory',

data: { orderId: 123 },

},

{

name: 'charge-payment',

queueName: 'payments',

data: { orderId: 123 },

},

{

name: 'notify-warehouse',

queueName: 'notifications',

data: { orderId: 123 },

},

],

});

Graceful Shutdown

Properly close workers without losing jobs

When to use: Deploying or restarting workers

const shutdown = async () => {

console.log('Shutting down gracefully...');

// Stop accepting new jobs

await worker.pause();

// Wait for current jobs to finish (with timeout)

await worker.close();

// Close queue connection

await queue.close();

process.exit(0);

};

process.on('SIGTERM', shutdown);

process.on('SIGINT', shutdown);

Bull Board Dashboard

Visual monitoring for BullMQ queues

When to use: Need visibility into queue status and job states

import { createBullBoard } from '@bull-board/api';

import { BullMQAdapter } from '@bull-board/api/bullMQAdapter';

import { ExpressAdapter } from '@bull-board/express';

const serverAdapter = new ExpressAdapter();

serverAdapter.setBasePath('/admin/queues');

createBullBoard({

queues: [

new BullMQAdapter(emailQueue),

new BullMQAdapter(orderQueue),

],

serverAdapter,

});

app.use('/admin/queues', serverAdapter.getRouter());

Validation Checks

Redis connection missing maxRetriesPerRequest

Severity: ERROR

BullMQ requires maxRetriesPerRequest null for proper reconnection handling

Message: BullMQ queue/worker created without maxRetriesPerRequest: null on Redis connection. This will cause workers to stop on Redis connection issues.

No stalled job event handler

Severity: WARNING

Workers should handle stalled events to detect crashed workers

Message: Worker created without 'stalled' event handler. Stalled jobs indicate worker crashes and should be monitored.

No failed job event handler

Severity: WARNING

Workers should handle failed events for monitoring and alerting

Message: Worker created without 'failed' event handler. Failed jobs should be logged and monitored.

No graceful shutdown handling

Severity: WARNING

Workers should gracefully shut down on SIGTERM/SIGINT

Message: Worker file without graceful shutdown handling. Jobs may be orphaned on deployment.

Unawaited queue.add in request handler

Severity: ERROR

Await queue insertion before reporting acceptance. Bound producer retries/timeouts so an unavailable Redis does not leave HTTP requests hanging; worker retry settings are different.

Potentially large data in job payload

Severity: WARNING

Job data should be small - pass IDs not full objects

Message: Job appears to have large inline data. Pass IDs instead of full objects to keep Redis memory low.

Job without timeout configuration

Severity: INFO

Jobs should have timeouts to prevent infinite execution

Message: Job added without explicit timeout. Consider adding timeout to prevent stuck jobs.

Retry without backoff strategy

Severity: WARNING

Retries should use exponential backoff to avoid thundering herd

Message: Job has retry attempts but no backoff strategy. Use exponential backoff to prevent thundering herd.

Repeatable job without explicit timezone

Severity: WARNING

Repeatable jobs should specify timezone to avoid DST issues

Message: Repeatable job without explicit timezone. Will use server local time which can drift with DST.

Potentially high worker concurrency

Severity: INFO

High concurrency can overwhelm downstream services

Message: Worker concurrency is high. Ensure downstream services can handle this load (DB connections, API rate limits).

Collaboration

Delegation Triggers

• redis infrastructure|redis cluster|memory tuning -> redis-specialist (Queue needs Redis infrastructure)
• serverless queue|edge queue|no redis -> upstash-qstash (Need queues without managing Redis)
• complex workflow|saga|compensation|long-running -> temporal-craftsman (Need workflow orchestration beyond simple jobs)
• event sourcing|CQRS|event streaming -> event-architect (Need event-driven architecture)
• deploy|kubernetes|scaling|infrastructure -> devops (Queue needs infrastructure)
• monitor|metrics|alerting|dashboard -> performance-hunter (Queue needs monitoring)

Email Queue Stack

Skills: bullmq-specialist, email-systems, redis-specialist

Workflow:

1. Email request received (API)
2. Job queued with rate limiting (bullmq-specialist)
3. Worker processes with backoff (bullmq-specialist)
4. Email sent via provider (email-systems)
5. Status tracked in Redis (redis-specialist)

Background Processing Stack

Skills: bullmq-specialist, backend, devops

Workflow:

1. API receives request (backend)
2. Long task q

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