bullmq-specialist

BullMQ Specialist

BullMQ expert for Redis-backed job queues, background processing, and reliable async execution in Node.js/TypeScript applications.

Principles

• Jobs are fire-and-forget from the producer side - let the queue handle delivery
• 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', });

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.

Awaiting queue.add in request handler

Severity: INFO

Queue additions should be fire-and-forget in request handlers

Message: Queue.add awaited in request handler. Consider fire-and-forget for faster response.

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