A job producer is simply some Node program that adds jobs to a queue, like this: As you can see a job is just a javascript object. Although you can implement a jobqueue making use of the native Redis commands, your solution will quickly grow in complexity as soon as you need it to cover concepts like: Then, as usual, youll end up making some research of the existing options to avoid re-inventing the wheel. : number) for reporting the jobs progress, log(row: string) for adding a log row to this job-specific job, moveToCompleted, moveToFailed, etc. Lets take as an example thequeue used in the scenario described at the beginning of the article, an image processor, to run through them. Jobs can be added to a queue with a priority value. If you want jobs to be processed in parallel, specify a concurrency argument. Support for LIFO queues - last in first out. How to measure time taken by a function to execute. View the Project on GitHub OptimalBits/bull. Your job processor was too CPU-intensive and stalled the Node event loop, and as a result, Bull couldn't renew the job lock (see #488 for how we might better detect this). I tried do the same with @OnGlobalQueueWaiting() but i'm unable to get a lock on the job. Bull 4.x concurrency being promoted to a queue-level option is something I'm looking forward to. With this, we will be able to use BullModule across our application. Bull Queue may be the answer. We fetch all the injected queues so far using getBullBoardQueuesmethod described above. Stalled jobs can be avoided by either making sure that the process function does not keep Node event loop busy for too long (we are talking several seconds with Bull default options), or by using a separate sandboxed processor. Well bull jobs are well distributed, as long as they consume the same topic on a unique redis. Redis stores only serialized data, so the task should be added to the queue as a JavaScript object, which is a serializable data format. The jobs can be small, message like, so that the queue can be used as a message broker, or they can be larger long running jobs. Bull processes jobs in the order in which they were added to the queue. Note that the concurrency is only possible when workers perform asynchronous operations such as a call to a database or a external HTTP service, as this is how node supports concurrency natively. Lets look at the configuration we have to add for Bull Queue. As soonas a workershowsavailability it will start processing the piled jobs. The list of available events can be found in the reference. Each queue instance can perform three different roles: job producer, job consumer, and/or events listener. Is it incorrect to say that Node.js & JavaScript offer a concurrency model based on the event loop?
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