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Reference

Queue

Queue(queueName: string, url?: string, opts?: QueueOptions): Queue

This is the Queue constructor. It creates a new Queue that is persisted in Redis. Everytime the same queue is instantiated it tries to process all the old jobs that may exist from a previous unfinished session.

The optional url argument, allows to specify a redis connection string such as for example: redis://mypassword@myredis.server.com:1234

interface QueueOptions {
  limiter?: RateLimiter;
  redis?: RedisOpts;
  prefix?: string = 'bull'; // prefix for all queue keys.
  settings?: AdvancedSettings;
}
interface RateLimiter {
  max: number,      // Max number of jobs processed
  duration: number, // per duration in milliseconds
}

RedisOpts are passed directly to ioredis constructor, check ioredis for details. We document here just the most important ones.

interface RedisOpts {
  port?: number = 6379;
  host?: string = localhost;
  db?: number = 0;
  password?: string;
}
interface AdvancedSettings {
  lockDuration: number = 30000; // Key expiration time for job locks.
  stalledInterval: number = 30000; // How often check for stalled jobs (use 0 for never checking).
  maxStalledCount: number = 1; // Max amount of times a stalled job will be re-processed.
  guardInterval: number = 5000; // Poll interval for delayed jobs and added jobs.s
  retryProcessDelay: number = 5000; // delay before processing next job in case of internal error.
  backoffStrategies: {}; // A set of custom backoff strategies keyed by name.
}

Advanced Settings

Warning: Do not override these advanced settings unless you understand the internals of the queue.

lockDuration: Time in milliseconds to acquire the job lock. Set this to a higher value if you find that your jobs are being stalled because your job processor is CPU-intensive and blocking the event loop (see note below about stalled jobs). Set this to a lower value if your jobs are extremely time-sensitive and it might be OK if they get double-processed (due to them be falsly considered stalled).

lockRenewTime: Interval in milliseconds on which to acquire the job lock. It is set to lockDuration / 2 by default to give enough buffer to renew the lock each time before the job lock expires. It should never be set to a value larger than lockDuration. Set this to a lower value if you're finding that jobs are becoming stalled due to a CPU-intensive job processor function. Generally you shouldn't change this though.

stalledInterval: Interval in milliseconds on which each worker will check for stalled jobs (i.e. unlocked jobs in the active state). See note below about stalled jobs. Set this to a lower value if your jobs are extremely time-sensitive. Set this to a higher value if your Redis CPU usage is high as this check can be expensive. Note that because each worker runs this on its own interval and checks the entire queue, the stalled job actually run much more frequently than this value would imply.

maxStalledCount: The maximum number of times a job can be restarted before it will be permamently failed with the error job stalled more than allowable limit. This is set to a default of 1 with the assumption that stalled jobs should be very rare (only due to process crashes) and you want to be on the safer side of not restarting jobs. Set this higher if stalled jobs are common (e.g. processes crash a lot) and it's generally OK to double process jobs.

guardInterval: Interval in milliseconds on which the delayed job watchdog will run. This watchdog is only in place for unstable Redis connections which can caused delayed jobs to not be processed. Set to a lower value if your Redis connection is unstable and delayed jobs aren't being processed in time.

retryProcessDelay: Time in milliseconds in which to wait before trying to process jobs, in case of a Redis error. Set to a lower value on an unstable Redis connection.

backoffStrategies: An object containing custom backoff strategies. The key in the object is the name of the strategy and the value is a function that should return the delay in milliseconds. For a full example see Patterns.

backoffStrategies: {
  jitter: function () {
    return 5000 + Math.random() * 500;
  }
}

Queue#process

/**
 * Consider these as overloaded functions. Since method overloading doesn't exist in javacript
 * bull recognizes the desired function call by checking the parameters' types. Make sure you
 * comply with one of the below defined patterns.
 *
 * Note: Concurrency defaults to 1 if not specified.
 */
process(processor: (job, done?) => Promise<any> | string)
process(concurrency: number, processor: (job, done?) => Promise<any> | string)
process(name: string, processor: (job, done?) => Promise<any> | string)
process(name: string, concurrency: number, processor: (job, done?) => Promise<any> | string)

Defines a processing function for the jobs in a given Queue.

The callback is called everytime a job is placed in the queue. It is passed an instance of the job as first argument.

If the callback signature contains the second optional done argument, the callback will be passed a done callback to be called after the job has been completed. The done callback can be called with an Error instance, to signal that the job did not complete successfully, or with a result as second argument as second argument (e.g.: done(null, result);) when the job is successful. Errors will be passed as a second argument to the "failed" event; results, as a second argument to the "completed" event.

If, however, the callback signature does not contain the done argument, a promise must be returned to signal job completion. If the promise is rejected, the error will be passed as a second argument to the "failed" event. If it is resolved, its value will be the "completed" event's second argument.

A process function can also be declared as a separate process. This will make a better use of the available CPU cores and run the jobs in parallel. This is a perfect way to run blocking code. Just specify an absolute path to a processor module. i.e. a file exporting the process function like this:

// my-processor.js
module.exports = function(job){
  // do some job

  return value;
}

You can return a value or a promise to signale that the job has been completed.

A name argument can be provided so that multiple process functions can be defined per queue. A named process will only process jobs that matches the given name. If you define multiple named process functions in one Queue the defined concurrency for each process function stacks up for the Queue. See the following examples:

/***
 * For each named processor concurrency stacks up, so any of these three process functions
 * can run with a concurrency of 125. To avoid this behaviour you need to create an own queue
 * for each process function.
 */
const loadBalancerQueue = new Queue('loadbalancer')
loadBalancerQueue.process('requestProfile', 100, requestProfile)
loadBalancerQueue.process('sendEmail', 25, sendEmail)
loadBalancerQueue.process('sendInvitation', 0, sendInvite)

const profileQueue = new Queue('profile')
// Max concurrency for requestProfile is 100
profileQueue.process('requestProfile', 100, requestProfile)

const emailQueue = new Queue('email')
// Max concurrency for sendEmail is 25
emailQueue.process('sendEmail', 25, sendEmail)

Note: in order to determine whether job completion is signaled by returning a promise or calling the done callback, Bull looks at the length property of the callback you pass to it. So watch out, as the following won't work:

// THIS WON'T WORK!!
queue.process(function(job, done) { // Oops! done callback here!
  return Promise.resolve();
});

This, however, will:

queue.process(function(job) { // No done callback here :)
  return Promise.resolve();
});

You can specify a concurrency. Bull will then call your handler in parallel respecting this maximum value.

Queue#add

add(name?: string, data: any, opts?: JobOpts): Promise<Job>

Creates a new job and adds it to the queue. If the queue is empty the job will be executed directly, otherwise it will be placed in the queue and executed as soon as possible.

An optional name can be added, so that only process functions defined for that name will process the job.

interface JobOpts{
  priority: number; // Optional priority value. ranges from 1 (highest priority) to MAX_INT  (lowest priority). Note that
                    // using priorities has a slight impact on performance, so do not use it if not required.

  delay: number; // An amount of miliseconds to wait until this job can be processed. Note that for accurate delays, both
                 // server and clients should have their clocks synchronized. [optional].

  attempts: number; // The total number of attempts to try the job until it completes.

  repeat: RepeatOpts; // Repeat job according to a cron specification.

  backoff: number | BackoffOpts; // Backoff setting for automatic retries if the job fails

  lifo: boolean; // if true, adds the job to the right of the queue instead of the left (default false)
  timeout: number; // The number of milliseconds after which the job should be fail with a timeout error [optional]

  jobId: number | string; // Override the job ID - by default, the job ID is a unique
                          // integer, but you can use this setting to override it.
                          // If you use this option, it is up to you to ensure the
                          // jobId is unique. If you attempt to add a job with an id that
                          // already exists, it will not be added.

  removeOnComplete: boolean; // If true, removes the job when it successfully
                            // completes. Default behavior is to keep the job in the completed set.

  removeOnFail: boolean; // If true, removes the job when it fails after all attempts.
                         // Default behavior is to keep the job in the failed set.
  stackTraceLimit: number; // Limits the amount of stack trace lines that will be recorded in the stacktrace.
}
interface RepeatOpts{
  cron: string; // Cron string
  tz?: string, // Timezone
  endDate?: Date | string | number; // End data when the repeat job should stop repeating.
}

More information regarding the cron expression

interface BackoffOpts{
  type: string; // Backoff type, which can be either `fixed` or `exponential`. A custom backoff strategy can also be specified in `backoffStrategies` on the queue settings.
  delay: number; // Backoff delay, in milliseconds.
}

Queue#pause

pause(isLocal?: boolean): Promise

Returns a promise that resolves when the queue is paused. A paused queue will not process new jobs until resumed, but current jobs being processed will continue until they are finalized. The pause can be either global or local. If global, all workers in all queue instances for a given queue will be paused. If local, just this worker will stop processing new jobs after the current lock expires. This can be useful to stop a worker from taking new jobs prior to shutting down.

Pausing a queue that is already paused does nothing.

Queue#resume

resume(isLocal?: boolean): Promise

Returns a promise that resolves when the queue is resumed after being paused. The resume can be either local or global. If global, all workers in all queue instances for a given queue will be resumed. If local, only this worker will be resumed. Note that resuming a queue globally will not resume workers that have been paused locally; for those, resume(true) must be called directly on their instances.

Resuming a queue that is not paused does nothing.

Queue#count

count(): Promise<number>

Returns a promise that returns the number of jobs in the queue, waiting or delayed. Since there may be other processes adding or processing jobs, this value may be true only for a very small amount of time.

Queue#empty

empty(): Promise

Empties a queue deleting all the input lists and associated jobs.

Queue#close

close(): Promise

Closes the underlying Redis client. Use this to perform a graceful shutdown.

var Queue = require('bull');
var queue = Queue('example');

var after100 = _.after(100, function () {
  queue.close().then(function () { console.log('done') })
});

queue.on('completed', after100);

close can be called from anywhere, with one caveat: if called from within a job handler the queue won't close until after the job has been processed, so the following won't work:

queue.process(function (job, jobDone) {
  handle(job);
  queue.close().then(jobDone);
});

Instead, do this:

queue.process(function (job, jobDone) {
  handle(job);
  queue.close();
  jobDone();
});

Or this:

queue.process(function (job) {
  queue.close();
  return handle(job).then(...);
});

Queue#getJob

getJob(jobId: string): Promise<Job>

Returns a promise that will return the job instance associated with the jobId parameter. If the specified job cannot be located, the promise will be resolved to null.

Queue#removeRepeatable

removeRepeatable(name?: string, repeat: RepeatOpts): Promise<void>

Removes a given repeatable job. The RepeatOpts needs to be the same as the ones used for the job when it was added.

Queue#getJobCounts

getJobCounts() : Promise<JobCounts>

Returns a promise that will return the job counts for the given queue.

  interface JobCounts {
    waiting: number,
    active: number,
    completed: number,
    failed: number,
    delayed: number
  }
}

Queue#getCompletedCount

getCompletedCount() : Promise<number>

Returns a promise that will return the completed job counts for the given queue.

Queue#getFailedCount

getFailedCount() : Promise<number>

Returns a promise that will return the failed job counts for the given queue.

Queue#getDelayedCount

getDelayedCount() : Promise<number>

Returns a promise that will return the delayed job counts for the given queue.

Queue#getActiveCount

getActiveCount() : Promise<number>

Returns a promise that will return the active job counts for the given queue.

Queue#getWaitingCount

getWaitingCount() : Promise<number>

Returns a promise that will return the waiting job counts for the given queue.

Queue#getPausedCount

getPausedCount() : Promise<number>

Returns a promise that will return the paused job counts for the given queue.

Queue#getWaiting

getWaiting(start?: number, end?: number) : Promise<Array<Job>>

Returns a promise that will return an array with the waiting jobs between start and end.

Queue#getActive

getActive(start?: number, end?: number) : Promise<Array<Job>>

Returns a promise that will return an array with the active jobs between start and end.

Queue#getDelayed

getDelayed(start?: number, end?: number) : Promise<Array<Job>>

Returns a promise that will return an array with the delayed jobs between start and end.

Queue#getCompleted

getCompleted(start?: number, end?: number) : Promise<Array<Job>>

Returns a promise that will return an array with the completed jobs between start and end.

Queue#getFailed

getFailed(start?: number, end?: number) : Promise<Array<Job>>

Returns a promise that will return an array with the failed jobs between start and end.

Queue#clean

clean(grace: number, status?: string, limit?: number): Promise<number[]>

Tells the queue remove jobs of a specific type created outside of a grace period.

Example

//cleans all jobs that completed over 5 seconds ago.
queue.clean(5000);
//clean all jobs that failed over 10 seconds ago.
queue.clean(10000, 'failed');
queue.on('cleaned', function (job, type) {
  console.log('Cleaned %s %s jobs', job.length, type);
});

Arguments

  grace: number; Grace period in milliseconds.
  status: string; Status of the job to clean. Values are completed, wait, active,
  delayed, and failed. Defaults to completed.
  limit: number; maximum amount of jobs to clean per call. If not provided will clean all matching jobs.

  returns Promise; A promise that resolves with an array of removed jobs.

Events

The cleaner emits the cleaned event anytime the queue is cleaned.

  queue.on('cleaned', listener: (jobs: number[], status: string) => void);

Job

A job includes all data needed to perform its execution, as well as the progress method needed to update its progress.

The most important property for the user is Job#data that includes the object that was passed to Queue#add, and that is normally used to perform the job.

Job#progress

progress(progress: number): Promise

Updates a job progress.

Arguments

  progress: number; Job progress between 0 and 100.

Job#getState

getState(): Promise

Returns a promise resolving to the current job's status (completed, failed, delayed etc.). Possible returns are: completed, failed, delayed, active, waiting, paused, stuck or null.

Please take note that the implementation of this method is not very efficient, nor is it atomic. If your queue does have a very large quantity of jobs, you may want to avoid using this method.

Job#update

update(data: object): Promise

Updated a job data field with the give data object.

Job#remove

remove(): Promise

Removes a job from the queue and from any lists it may be included in.

Job#retry

retry(): Promise

Re-run a job that has failed. Returns a promise that resolves when the job is scheduled for retry.

Job#discard

discard(): Promise

Ensure this job is never ran again even if attemptsMade is less than job.attempts.

Job#promote

promote(): Promise

Promotes a job that is currently "delayed" to the "waiting" state and executed as soon as possible.

Job#finished

finished(): Promise

Returns a promise that resolves or rejects when the job completes or fails.

Events

A queue emits also some useful events:

.on('error', function(error) {
  // An error occured.
})

.on('active', function(job, jobPromise){
  // A job has started. You can use `jobPromise.cancel()`` to abort it.
})

.on('stalled', function(job){
  // A job has been marked as stalled. This is useful for debugging job
  // workers that crash or pause the event loop.
})

.on('progress', function(job, progress){
  // A job's progress was updated!
})

.on('completed', function(job, result){
  // A job successfully completed with a `result`.
})

.on('failed', function(job, err){
  // A job failed with reason `err`!
})

.on('paused', function(){
  // The queue has been paused.
})

.on('resumed', function(job){
  // The queue has been resumed.
})

.on('cleaned', function(jobs, type) {
  // Old jobs have been cleaned from the queue. `jobs` is an array of cleaned
  // jobs, and `type` is the type of jobs cleaned.
});

Global events

Events are local by default — in other words, they only fire on the listeners that are registered on the given worker. If you need to listen to events globally, for example from other servers across redis, just prefix the event with 'global:':

// Will listen locally, just to this queue...
queue.on('completed', listener):

// Will listen globally, to instances of this queue...
queue.on('global:completed', listener);

When working with global events whose local counterparts pass a Job instance to the event listener callback, notice that global events pass the job's ID instead.

If you need to access the Job instance in a global listener, use Queue#getJob to retrieve it. However, remember that if removeOnComplete is enabled when adding the job, the job will no longer be available after completion. Should you need to both access the job and remove it after completion, you can use Job#remove to remove it in the listener.

// Local events pass the job instance...
queue.on('progress', function(job, progress) {
  console.log(`Job ${job.id} is ${progress * 100}% ready!`);
});

queue.on('completed', function(job, result) {
  console.log(`Job ${job.id} completed! Result: ${result}`);
  job.remove();
});

// ...whereas global events only pass the job ID:
queue.on('global:progress', function(jobId, progress) {
  console.log(`Job ${jobId} is ${progress * 100}% ready!`);
});

queue.on('global:completed', function(jobId, result) {
  console.log(`Job ${jobId} completed! Result: ${result}`);
  queue.getJob(jobId).then(function(job) {
    job.remove();
  });
});