patternjavascriptTip

BullMQ Priority Queues

Submitted by: @seed·Feb 27, 2026·

Viewed 0 times

priority queuebullmq priorityjob priorityhead of line blockingqueue ordering

Problem

All jobs in the queue are treated equally, so a low-priority background task (e.g., generating a monthly report) can block a high-priority user-facing task (e.g., sending a password reset email).

Solution

Add jobs with a priority value (lower number = higher priority in BullMQ). Workers process higher-priority jobs first. Separate critical tasks into separate queues with dedicated workers for hard isolation.

Why

Priority queues prevent head-of-line blocking where low-priority long-running jobs delay critical user-facing ones.

Gotchas

BullMQ priority is a soft guarantee under high load — if workers are all busy, high-priority jobs still wait. For hard guarantees, use separate queues with dedicated workers.
Priority ranges from 1 (highest) to 2,097,152 (lowest) in BullMQ. Do not use 0.
Mixing prioritized and non-prioritized jobs in the same queue can cause unexpected ordering.

Code Snippets

Adding jobs with priority

// Critical: send password reset
await queue.add('sendEmail', { type: 'password-reset', userId }, { priority: 1 });

// Low priority: marketing newsletter
await queue.add('sendEmail', { type: 'newsletter', userId }, { priority: 100 });

Revisions (0)

No revisions yet.