BullMQ
  • What is BullMQ
  • Quick Start
  • API Reference
  • Changelogs
    • v4
    • v3
    • v2
    • v1
  • Guide
    • Introduction
    • Connections
    • Queues
      • Auto-removal of jobs
      • Adding jobs in bulk
      • Global Concurrency
      • Removing Jobs
    • Workers
      • Auto-removal of jobs
      • Concurrency
      • Graceful shutdown
      • Stalled Jobs
      • Sandboxed processors
      • Pausing queues
    • Jobs
      • FIFO
      • LIFO
      • Job Ids
      • Job Data
      • Deduplication
      • Delayed
      • Repeatable
      • Prioritized
      • Removing jobs
      • Stalled
      • Getters
    • Job Schedulers
      • Repeat Strategies
      • Repeat options
      • Manage Job Schedulers
    • Flows
      • Adding flows in bulk
      • Get Flow Tree
      • Fail Parent
      • Continue Parent
      • Remove Dependency
      • Ignore Dependency
      • Remove Child Dependency
    • Metrics
      • Prometheus
    • Rate limiting
    • Parallelism and Concurrency
    • Retrying failing jobs
    • Returning job data
    • Events
      • Create Custom Events
    • Telemetry
      • Getting started
      • Running Jaeger
      • Running a simple example
    • QueueScheduler
    • Redisâ„¢ Compatibility
      • Dragonfly
    • Redisâ„¢ hosting
      • AWS MemoryDB
      • AWS Elasticache
    • Architecture
    • NestJs
      • Producers
      • Queue Events Listeners
    • Going to production
    • Migration to newer versions
    • Troubleshooting
  • Patterns
    • Adding jobs in bulk across different queues
    • Manually processing jobs
    • Named Processor
    • Flows
    • Idempotent jobs
    • Throttle jobs
    • Process Step Jobs
    • Failing fast when Redis is down
    • Stop retrying jobs
    • Timeout jobs
    • Timeout for Sandboxed processors
    • Redis Cluster
  • BullMQ Pro
    • Introduction
    • Install
    • Observables
      • Cancelation
    • Groups
      • Getters
      • Rate limiting
      • Local group rate limit
      • Concurrency
      • Local group concurrency
      • Max group size
      • Pausing groups
      • Prioritized intra-groups
      • Sandboxes for groups
    • Telemetry
    • Batches
    • NestJs
      • Producers
      • Queue Events Listeners
      • API Reference
      • Changelog
    • API Reference
    • Changelog
    • New Releases
    • Support
  • Bull
    • Introduction
    • Install
    • Quick Guide
    • Important Notes
    • Reference
    • Patterns
      • Persistent connections
      • Message queue
      • Returning Job Completions
      • Reusing Redis Connections
      • Redis cluster
      • Custom backoff strategy
      • Debugging
      • Manually fetching jobs
  • Python
    • Introduction
    • Changelog
Powered by GitBook

Copyright (c) Taskforce.sh Inc.

On this page

Was this helpful?

  1. Guide
  2. Workers

Stalled Jobs

Due to the nature of NodeJS, which is (in general) single threaded and consists of an event loop to handle the asynchronous operations, the process function needs to be written carefully so that the CPU is not occupied for a long time.

When a job reaches a worker and starts to be processed, BullMQ will place a lock on this job to protect the job from being modified by any other client or worker. At the same time, the worker needs to periodically notify BullMQ that it is still working on the job.

This period is configured with the stalledInterval setting, which normally you should not need to modify.

However if the CPU is very busy (due to the process being very CPU intensive), the worker may not have time to renew the lock and tell the queue that it is still working on the job, which is likely to result in the job being marked as stalled.

A stalled job is moved back to the waiting status and will be processed again by another worker, or if it has reached its maximum number of stalls, it will be moved to the failed set.

Therefore, it is very important to make sure the workers return control to the NodeJS event loop often enough to avoid this kind of problem.

PreviousGraceful shutdownNextSandboxed processors

Last updated 10 months ago

Was this helpful?