Compatibility class

The Queue3 class is targeted to simplify migration of projects based on Bull 3. Though it does not offer 100% API and functional compatibility, upgrading to BullMQ with this class should be easier for users familiar with Bull 3.

Differences in interface include

  • fixed order of add() and process() method arguments

  • class instantiation requires use of the new operator

  • interfaces for Queue and Job options and Job class do not have wrappers and are used directly

  • there's no done argument expected in process() callback anymore; now the callback must always return a Promise object

  • name property is mandatory in add() method

  • concurrency is moved from process() argument to queue options

Functional differences generally include only the absence of named processors feature and minor changes in local and global events set. The mandatory name property in add() method can contain any string and gets saved to Redis as is. When a job is in progress, you can read this value using ( and are available as usual). See the [link] for details.

The all-in-one example:

import { Job } from "bullmq";
import { Queue3 } from "bullmq/dist/classes/compat";

const queue = new Queue3("animals", { concurrency: 1 });

queue.process(async (job: Job) => {
   return `${}s ${}ing`;

queue.on("completed", (job: Job, result: any) => {
   console.log(`Job ${} is completed with result: ${result}`);

queue.add("cat", { sound: "meow" });
queue.add("cow", { sound: "moo" });
queue.add("dog", { sound: "bark" });

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