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Rate limiting

BullMQ provides rate limiting for the queues. It is possible to configure the workers so that they obey a given rate limiting option:

import { Worker, QueueScheduler } from 'bullmq';

const worker = new Worker('painter', async job => paintCar(job), {
  limiter: {
    max: 10,
    duration: 1000,
  },
});

const scheduler = new QueueScheduler('painter');

{% hint style="warning" %} Jobs that get rate limited will actually stay in waiting state. {% endhint %}

{% hint style="danger" %} From BullMQ 2.0 and onwards, the QueueScheduler is not needed anymore. {% endhint %}

{% hint style="info" %} The rate limiter is global, so if you have for example 10 workers for one queue with the above settings, still only 10 jobs will be processed by second. {% endhint %}

Group keys

{% hint style="danger" %} From BullMQ 3.0 and onwards, group keys support is removed to improve global rate limit, so the information below is only valid for older versions. {% endhint %}

It is also possible to define a rate limiter based on group keys, for example you may want to have a rate limiter per customer instead of a global rate limiter for all customers:

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

const queue = new Queue('painter', {
  limiter: {
    groupKey: 'customerId',
  },
});

const worker = new Worker('painter', async job => paintCar(job), {
  limiter: {
    max: 10,
    duration: 1000,
    groupKey: 'customerId',
  },
});

const scheduler = new QueueScheduler('painter');

// jobs will be rate limited by the value of customerId key:
await queue.add('rate limited paint', { customerId: 'my-customer-id' });

Manual rate-limit

Sometimes is useful to rate-limit a queue manually instead of based on some static options. For example, if you have an API that returns 429 (Too many requests), and you want to rate-limit the queue based on that response.

For this purpose, you can use the worker method rateLimit like this:

import { Worker } from 'bullmq';

const worker = new Worker(
  'myQueue',
  async () => {
    const [isRateLimited, duration] = await doExternalCall();
    if (isRateLimited) {
      await worker.rateLimit(duration);
      // Do not forget to throw this special exception,
      // since the job is no longer active after being rate limited.
      throw Worker.RateLimitError();
    }
  },
  {
    connection,
  },
);

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