a fork of kue
npm install @gaoding/kue
Kue is a priority job queue backed by redis, built for node.js.
PROTIP This is the latest Kue documentation, make sure to also read the changelist.
- Latest release:
$ npm install kue
- Master branch:
$ npm install http://github.com/Automattic/kue/tarball/master
- Delayed jobs
- Distribution of parallel work load
- Job event and progress pubsub
- Job TTL
- Optional retries with backoff
- Graceful workers shutdown
- Full-text search capabilities
- RESTful JSON API
- Rich integrated UI
- Infinite scrolling
- UI progress indication
- Job specific logging
- Powered by Redis
- Creating Jobs
- Jobs Priority
- Failure Attempts
- Failure Backoff
- Job TTL
- Job Logs
- Job Progress
- Job Events
- Queue Events
- Delayed Jobs
- Processing Jobs
- Processing Concurrency
- Pause Processing
- Updating Progress
- Graceful Shutdown
- Error Handling
- Queue Maintenance
- Redis Connection Settings
- User-Interface
- JSON API
- Parallel Processing With Cluster
- Securing Kue
- Testing
- Screencasts
- License
First create a job Queue with kue.createQueue():
``js`
var kue = require('kue')
, queue = kue.createQueue();
Calling queue.create() with the type of job ("email"), and arbitrary job data will return a Job, which can then be save()ed, adding it to redis, with a default priority level of "normal". The save() method optionally accepts a callback, responding with an error if something goes wrong. The title key is special-cased, and will display in the job listings within the UI, making it easier to find a specific job.
`js`
var job = queue.create('email', {
title: 'welcome email for tj'
, to: 'tj@learnboost.com'
, template: 'welcome-email'
}).save( function(err){
if( !err ) console.log( job.id );
});
To specify the priority of a job, simply invoke the priority() method with a number, or priority name, which is mapped to a number.
`js`
queue.create('email', {
title: 'welcome email for tj'
, to: 'tj@learnboost.com'
, template: 'welcome-email'
}).priority('high').save();
The default priority map is as follows:
`js`
{
low: 10
, normal: 0
, medium: -5
, high: -10
, critical: -15
};
By default jobs only have _one_ attempt, that is when they fail, they are marked as a failure, and remain that way until you intervene. However, Kue allows you to specify this, which is important for jobs such as transferring an email, which upon failure, may usually retry without issue. To do this invoke the .attempts() method with a number.
`js`
queue.create('email', {
title: 'welcome email for tj'
, to: 'tj@learnboost.com'
, template: 'welcome-email'
}).priority('high').attempts(5).save();
. If you want to delay job re-attempts upon failures (known as backoff) you can use Job#backoff method in different ways:`js
// Honor job's original delay (if set) at each attempt, defaults to fixed backoff
job.attempts(3).backoff( true ) // Override delay value, fixed backoff
job.attempts(3).backoff( {delay: 60*1000, type:'fixed'} )
// Enable exponential backoff using original delay (if set)
job.attempts(3).backoff( {type:'exponential'} )
// Use a function to get a customized next attempt delay value
job.attempts(3).backoff( function( attempts, delay ){
//attempts will correspond to the nth attempt failure so it will start with 0
//delay will be the amount of the last delay, not the initial delay unless attempts === 0
return my_customized_calculated_delay;
})
`In the last scenario, provided function will be executed (via eval) on each re-attempt to get next attempt delay value, meaning that you can't reference external/context variables within it.
$3
Job producers can set an expiry value for the time their job can live in active state, so that if workers didn't reply in timely fashion, Kue will fail it with
error message preventing that job from being stuck in active state and spoiling concurrency.`js
queue.create('email', {title: 'email job with TTL'}).ttl(milliseconds).save();
`$3
Job-specific logs enable you to expose information to the UI at any point in the job's life-time. To do so simply invoke
, which accepts a message string as well as variable-arguments for sprintf-like support:`js
job.log('$%d sent to %s', amount, user.name);
`or anything else (uses util.inspect() internally):
js
job.log({key: 'some key', value: 10});
job.log([1,2,3,5,8]);
job.log(10.1);
`$3
Job progress is extremely useful for long-running jobs such as video conversion. To update the job's progress simply invoke
:`js
job.progress(frames, totalFrames);
`data can be used to pass extra information about the job. For example a message or an object with some extra contextual data to the current status.
$3
Job-specific events are fired on the
instances via Redis pubsub. The following events are currently supported:-
enqueue the job is now queued
- start the job is now running
- promotion the job is promoted from delayed state to queued
- progress the job's progress ranging from 0-100
- failed attempt the job has failed, but has remaining attempts yet
- failed the job has failed and has no remaining attempts
- complete the job has completed
- remove the job has been removed
For example this may look something like the following:
`js
var job = queue.create('video conversion', {
title: 'converting loki\'s to avi'
, user: 1
, frames: 200
});job.on('complete', function(result){
console.log('Job completed with data ', result);
}).on('failed attempt', function(errorMessage, doneAttempts){
console.log('Job failed');
}).on('failed', function(errorMessage){
console.log('Job failed');
}).on('progress', function(progress, data){
console.log('\r job #' + job.id + ' ' + progress + '% complete with data ', data );
});
`Note that Job level events are not guaranteed to be received upon process restarts, since restarted node.js process will lose the reference to the specific Job object. If you want a more reliable event handler look for Queue Events.
Note Kue stores job objects in memory until they are complete/failed to be able to emit events on them. If you have a huge concurrency in uncompleted jobs, turn this feature off and use queue level events for better memory scaling.
js
kue.createQueue({jobEvents: false})
` Alternatively, you can use the job level function
to control whether events are fired for a job at the job level.
`js
var job = queue.create('test').events(false).save();
`$3
Queue-level events provide access to the job-level events previously mentioned, however scoped to the
instance to apply logic at a "global" level. An example of this is removing completed jobs:`js
queue.on('job enqueue', function(id, type){
console.log( 'Job %s got queued of type %s', id, type );}).on('job complete', function(id, result){
kue.Job.get(id, function(err, job){
if (err) return;
job.remove(function(err){
if (err) throw err;
console.log('removed completed job #%d', job.id);
});
});
});
`The events available are the same as mentioned in "Job Events", however prefixed with "job ".
$3
Delayed jobs may be scheduled to be queued for an arbitrary distance in time by invoking the
method, passing the number of milliseconds relative to _now_. Alternatively, you can pass a JavaScript Date object with a specific time in the future.
This automatically flags the Job as "delayed".`js
var email = queue.create('email', {
title: 'Account renewal required'
, to: 'tj@learnboost.com'
, template: 'renewal-email'
}).delay(milliseconds)
.priority('high')
.save();
`Kue will check the delayed jobs with a timer, promoting them if the scheduled delay has been exceeded, defaulting to a check of top 1000 jobs every second.
Processing Jobs
Processing jobs is simple with Kue. First create a
instance much like we do for creating jobs, providing us access to redis etc, then invoke queue.process() with the associated type.
Note that unlike what the name createQueue suggests, it currently returns a singleton Queue instance. So you can configure and use only a single Queue object within your node.js process.In the following example we pass the callback
done to email, When an error occurs we invoke done(err) to tell Kue something happened, otherwise we invoke done() only when the job is complete. If this function responds with an error it will be displayed in the UI and the job will be marked as a failure. The error object passed to done, should be of standard type Error.`js
var kue = require('kue')
, queue = kue.createQueue();queue.process('email', function(job, done){
email(job.data.to, done);
});
function email(address, done) {
if(!isValidEmail(address)) {
//done('invalid to address') is possible but discouraged
return done(new Error('invalid to address'));
}
// email send stuff...
done();
}
`Workers can also pass job result as the second parameter to done
to store that in Job.result key. result is also passed through complete event handlers so that job producers can receive it if they like to.$3
By default a call to
queue.process() will only accept one job at a time for processing. For small tasks like sending emails this is not ideal, so we may specify the maximum active jobs for this type by passing a number:`js
queue.process('email', 20, function(job, done){
// ...
});
`$3
Workers can temporarily pause and resume their activity. That is, after calling
they will receive no jobs in their process callback until resume is called. The pause function gracefully shutdowns this worker, and uses the same internal functionality as the shutdown method in Graceful Shutdown.`js
queue.process('email', function(job, ctx, done){
ctx.pause( 5000, function(err){
console.log("Worker is paused... ");
setTimeout( function(){ ctx.resume(); }, 10000 );
});
});
`Note The
parameter from Kue >=0.9.0 is the second argument of the process callback function and done is idiomatically always the lastNote The
pause method signature is changed from Kue >=0.9.0 to move the callback function to the last.$3
For a "real" example, let's say we need to compile a PDF from numerous slides with node-canvas. Our job may consist of the following data, note that in general you should _not_ store large data in the job it-self, it's better to store references like ids, pulling them in while processing.
`js
queue.create('slideshow pdf', {
title: user.name + "'s slideshow"
, slides: [...] // keys to data stored in redis, mongodb, or some other store
});
`We can access this same arbitrary data within a separate process while processing, via the
property. In the example we render each slide one-by-one, updating the job's log and progress.`js
queue.process('slideshow pdf', 5, function(job, done){
var slides = job.data.slides
, len = slides.length; function next(i) {
var slide = slides[i]; // pretend we did a query on this slide id ;)
job.log('rendering %dx%d slide', slide.width, slide.height);
renderSlide(slide, function(err){
if (err) return done(err);
job.progress(i, len, {nextSlide : i == len ? 'itsdone' : i + 1});
if (i == len) done()
else next(i + 1);
});
}
next(0);
});
`$3
signals all workers to stop processing after their current active job is done. Workers will wait timeout milliseconds for their active job's done to be called or mark the active job failed with shutdown error reason. When all workers tell Kue they are stopped fn is called.`javascript
var queue = require('kue').createQueue();process.once( 'SIGTERM', function ( sig ) {
queue.shutdown( 5000, function(err) {
console.log( 'Kue shutdown: ', err||'' );
process.exit( 0 );
});
});
`Note that
method signature is changed from Kue >=0.9.0 to move the callback function to the last.Error Handling
All errors either in Redis client library or Queue are emitted to the
Queue object. You should bind to error events to prevent uncaught exceptions or debug kue errors.`javascript
var queue = require('kue').createQueue();queue.on( 'error', function( err ) {
console.log( 'Oops... ', err );
});
`$3
Kue marks a job complete/failed when
is called by your worker, so you should use proper error handling to prevent uncaught exceptions in your worker's code and node.js process exiting before in handle jobs get done.
This can be achieved in two ways:1. Wrapping your worker's process function in Domains
`js
queue.process('my-error-prone-task', function(job, done){
var domain = require('domain').create();
domain.on('error', function(err){
done(err);
});
domain.run(function(){ // your process function
throw new Error( 'bad things happen' );
done();
});
});
`
Notice - Domains are deprecated from Nodejs with stability 0 and it's not recommended to use. This is the softest and best solution, however is not built-in with Kue. Please refer to this discussion. You can comment on this feature in the related open Kue issue.
You can also use promises to do something like
js
queue.process('my-error-prone-task', function(job, done){
Promise.method( function(){ // your process function
throw new Error( 'bad things happen' );
})().nodeify(done)
});
` but this won't catch exceptions in your async call stack as domains do.
2. Binding to
and gracefully shutting down the Kue, however this is not a recommended error handling idiom in javascript since you are losing the error context.
`js
process.once( 'uncaughtException', function(err){
console.error( 'Something bad happened: ', err );
queue.shutdown( 1000, function(err2){
console.error( 'Kue shutdown result: ', err2 || 'OK' );
process.exit( 0 );
});
});
`$3
Kue currently uses client side job state management and when redis crashes in the middle of that operations, some stuck jobs or index inconsistencies will happen. The consequence is that certain number of jobs will be stuck, and be pulled out by worker only when new jobs are created, if no more new jobs are created, they stuck forever. So we strongly suggest that you run watchdog to fix this issue by calling:
js
queue.watchStuckJobs(interval)
` is in milliseconds and defaults to 1000msKue will be refactored to fully atomic job state management from version 1.0 and this will happen by lua scripts and/or BRPOPLPUSH combination. You can read more here and here.
Queue Maintenance
Queue object has two type of methods to tell you about the number of jobs in each state
`js
queue.inactiveCount( function( err, total ) { // others are activeCount, completeCount, failedCount, delayedCount
if( total > 100000 ) {
console.log( 'We need some back pressure here' );
}
});
`you can also query on an specific job type:
js
queue.failedCount( 'my-critical-job', function( err, total ) {
if( total > 10000 ) {
console.log( 'This is tOoOo bad' );
}
});
`and iterating over job ids
js
queue.inactive( function( err, ids ) { // others are active, complete, failed, delayed
// you may want to fetch each id to get the Job object out of it...
});
`however the second one doesn't scale to large deployments, there you can use more specific
static methods:`js
kue.Job.rangeByState( 'failed', 0, n, 'asc', function( err, jobs ) {
// you have an array of maximum n Job objects here
});
`
orjs
kue.Job.rangeByType( 'my-job-type', 'failed', 0, n, 'asc', function( err, jobs ) {
// you have an array of maximum n Job objects here
});
`Note that the last two methods are subject to change in later Kue versions.
$3
If you did none of above in Error Handling section or your process lost active jobs in any way, you can recover from them when your process is restarted. A blind logic would be to re-queue all stuck jobs:
js
queue.active( function( err, ids ) {
ids.forEach( function( id ) {
kue.Job.get( id, function( err, job ) {
// Your application should check if job is a stuck one
job.inactive();
});
});
});
`Note in a clustered deployment your application should be aware not to involve a job that is valid, currently inprocess by other workers.
$3
Jobs data and search indexes eat up redis memory space, so you will need some job-keeping process in real world deployments. Your first chance is using automatic job removal on completion.
javascript
queue.create( ... ).removeOnComplete( true ).save()
`But if you eventually/temporally need completed job data, you can setup an on-demand job removal script like below to remove top
completed jobs:`js
kue.Job.rangeByState( 'complete', 0, n, 'asc', function( err, jobs ) {
jobs.forEach( function( job ) {
job.remove( function(){
console.log( 'removed ', job.id );
});
});
});
`Note that you should provide enough time for
calls on each job object to complete before your process exits, or job indexes will leak
Redis Connection Settings
By default, Kue will connect to Redis using the client default settings (port defaults to
6379, host defaults to 127.0.0.1, prefix defaults to q). Queue#createQueue(options) accepts redis connection options in options.redis key.`javascript
var kue = require('kue');
var q = kue.createQueue({
prefix: 'q',
redis: {
port: 1234,
host: '10.0.50.20',
auth: 'password',
db: 3, // if provided select a non-default redis db
options: {
// see https://github.com/mranney/node_redis#rediscreateclient
}
}
});
` controls the key names used in Redis. By default, this is simply q. Prefix generally shouldn't be changed unless you need to use one Redis instance for multiple apps. It can also be useful for providing an isolated testbed across your main application.You can also specify the connection information as a URL string.
`js
var q = kue.createQueue({
redis: 'redis://example.com:1234?redis_option=value&redis_option=value'
});
`#### Connecting using Unix Domain Sockets
Since node_redis supports Unix Domain Sockets, you can also tell Kue to do so. See unix-domain-socket for your redis server configuration.
javascript
var kue = require('kue');
var q = kue.createQueue({
prefix: 'q',
redis: {
socket: '/data/sockets/redis.sock',
auth: 'password',
options: {
// see https://github.com/mranney/node_redis#rediscreateclient
}
}
});
`#### Replacing Redis Client Module
Any node.js redis client library that conforms (or when adapted) to node_redis API can be injected into Kue. You should only provide a
function as a redis connection factory instead of providing node_redis connection options.Below is a sample code to enable redis-sentinel to connect to Redis Sentinel for automatic master/slave failover.
`javascript
var kue = require('kue');
var Sentinel = require('redis-sentinel');
var endpoints = [
{host: '192.168.1.10', port: 6379},
{host: '192.168.1.11', port: 6379}
];
var opts = options || {}; // Standard node_redis client options
var masterName = 'mymaster';
var sentinel = Sentinel.Sentinel(endpoints);var q = kue.createQueue({
redis: {
createClientFactory: function(){
return sentinel.createClient(masterName, opts);
}
}
});
`Note that all
client codes should be refactored to pass redis options to Queue#createQueue instead of monkey patched style overriding of redis#createClient or they will be broken from Kue 0.8.x.#### Using ioredis client with cluster support
`javascriptvar Redis = require('ioredis');
var kue = require('kue');
// using https://github.com/72squared/vagrant-redis-cluster
var queue = kue.createQueue({
redis: {
createClientFactory: function () {
return new Redis.Cluster([{
port: 7000
}, {
port: 7001
}]);
}
}
});
`User-Interface
The UI is a small Express application.
A script is provided in
for running the interface as a standalone application
with default settings. You may pass in options for the port, redis-url, and prefix. For example:`
node_modules/kue/bin/kue-dashboard -p 3050 -r redis://127.0.0.1:3000 -q prefix
You can fire it up from within another application too:
js
var kue = require('kue');
kue.createQueue(...);
kue.app.listen(3000);
`The title defaults to "Kue", to alter this invoke:
js
kue.app.set('title', 'My Application');
`Note that if you are using non-default Kue options,
must be called before accessing kue.app.$3
You can also use Kue-UI web interface contributed by Arnaud Bénard
JSON API
Along with the UI Kue also exposes a JSON API, which is utilized by the UI.
$3
Query jobs, for example "GET /job/search?q=avi video":
`js
["5", "7", "10"]
`By default kue indexes the whole Job data object for searching, but this can be customized via calling
to tell kue which keys on Job data to create index for:`javascript
var kue = require('kue');
queue = kue.createQueue();
queue.create('email', {
title: 'welcome email for tj'
, to: 'tj@learnboost.com'
, template: 'welcome-email'
}).searchKeys( ['to', 'title'] ).save();
`Search feature is turned off by default from Kue
. Read more about this here. You should enable search indexes and add reds in your dependencies if you need to:`javascript
var kue = require('kue');
q = kue.createQueue({
disableSearch: false
});
`
npm install reds --save
$3
Currently responds with state counts, and worker activity time in milliseconds:
js
{"inactiveCount":4,"completeCount":69,"activeCount":2,"failedCount":0,"workTime":20892}
`$3
Get a job by
:`js
{"id":"3","type":"email","data":{"title":"welcome email for tj","to":"tj@learnboost.com","template":"welcome-email"},"priority":-10,"progress":"100","state":"complete","attempts":null,"created_at":"1309973155248","updated_at":"1309973155248","duration":"15002"}
`$3
Get job
's log:`js
['foo', 'bar', 'baz']
`$3
Get jobs with the specified range
to :to, for example "/jobs/0..2", where :order may be "asc" or "desc":`js
[{"id":"12","type":"email","data":{"title":"welcome email for tj","to":"tj@learnboost.com","template":"welcome-email"},"priority":-10,"progress":0,"state":"active","attempts":null,"created_at":"1309973299293","updated_at":"1309973299293"},{"id":"130","type":"email","data":{"title":"welcome email for tj","to":"tj@learnboost.com","template":"welcome-email"},"priority":-10,"progress":0,"state":"active","attempts":null,"created_at":"1309975157291","updated_at":"1309975157291"}]
`$3
Same as above, restricting by
which is one of: - active
- inactive
- failed
- complete
$3
Same as above, however restricted to
:type and :state.$3
Delete job
:id: $ curl -X DELETE http://local:3000/job/2
{"message":"job 2 removed"}
$3
Create a job:
$ curl -H "Content-Type: application/json" -X POST -d \
'{
"type": "email",
"data": {
"title": "welcome email for tj",
"to": "tj@learnboost.com",
"template": "welcome-email"
},
"options" : {
"attempts": 5,
"priority": "high"
}
}' http://localhost:3000/job
{"message": "job created", "id": 3}
You can create multiple jobs at once by passing an array. In this case, the response will be an array too, preserving the order:
$ curl -H "Content-Type: application/json" -X POST -d \
'[{
"type": "email",
"data": {
"title": "welcome email for tj",
"to": "tj@learnboost.com",
"template": "welcome-email"
},
"options" : {
"attempts": 5,
"priority": "high"
}
},
{
"type": "email",
"data": {
"title": "followup email for tj",
"to": "tj@learnboost.com",
"template": "followup-email"
},
"options" : {
"delay": 86400,
"attempts": 5,
"priority": "high"
}
}]' http://localhost:3000/job
[
{"message": "job created", "id": 4},
{"message": "job created", "id": 5}
]
Note: when inserting multiple jobs in bulk, if one insertion fails Kue will keep processing the remaining jobs in order. The response array will contain the ids of the jobs added successfully, and any failed element will be an object describing the error:
{"error": "error reason"}.
Parallel Processing With Cluster
The example below shows how you may use Cluster to spread the job processing load across CPUs. Please see Cluster module's documentation for more detailed examples on using it.
When cluster
.isMaster the file is being executed in context of the master process, in which case you may perform tasks that you only want once, such as starting the web app bundled with Kue. The logic in the else block is executed _per worker_.`js
var kue = require('kue')
, cluster = require('cluster')
, queue = kue.createQueue();var clusterWorkerSize = require('os').cpus().length;
if (cluster.isMaster) {
kue.app.listen(3000);
for (var i = 0; i < clusterWorkerSize; i++) {
cluster.fork();
}
} else {
queue.process('email', 10, function(job, done){
var pending = 5
, total = pending;
var interval = setInterval(function(){
job.log('sending!');
job.progress(total - pending, total);
--pending || done();
pending || clearInterval(interval);
}, 1000);
});
}
`Muti hosts deploy
Muti kue deploy on muti hosts, the master kue be in charge of checking the queue and broadcast the job's event, the woker same to the worker which work in a single kue deployment. but the workers are working in a interfering mode.js
var kue = require('kue');// create a kue only mater
var queue = kue.createQueue({
wokerType: Queue.MASTER // default Queue.MATER_WORKER
});
// create a worker
var queue = kue.createQueue({
wokerType: Queue.WORKER // Queue.MATER_WORKER
});
// create a master & worker
var queue = kue.createQueue({
wokerType: Queue.MATER_WORKER // Queue.MATER_WORKER
});
`This will create an
job processor (worker) per each of your machine CPU cores, with each you can handle 10 concurrent email jobs, leading to total 10 * N concurrent email jobs processed in your N core machine.Now when you visit Kue's UI in the browser you'll see that jobs are being processed roughly
N times faster! (if you have N cores).Securing Kue
Through the use of app mounting you may customize the web application, enabling TLS, or adding additional middleware like
basic-auth-connect.`bash
$ npm install --save basic-auth-connect
`js
var basicAuth = require('basic-auth-connect');
var app = express.createServer({ ... tls options ... });
app.use(basicAuth('foo', 'bar'));
app.use(kue.app);
app.listen(3000);
`Testing
Enable test mode to push all jobs into a
array. Make assertions against
the jobs in that array to ensure code under test is correctly enqueuing jobs.`js
queue = require('kue').createQueue();before(function() {
queue.testMode.enter();
});
afterEach(function() {
queue.testMode.clear();
});
after(function() {
queue.testMode.exit()
});
it('does something cool', function() {
queue.createJob('myJob', { foo: 'bar' }).save();
queue.createJob('anotherJob', { baz: 'bip' }).save();
expect(queue.testMode.jobs.length).to.equal(2);
expect(queue.testMode.jobs[0].type).to.equal('myJob');
expect(queue.testMode.jobs[0].data).to.eql({ foo: 'bar' });
});
`IMPORTANT: By default jobs aren't processed when created during test mode. You can enable job processing by passing true to testMode.enter
js
before(function() {
queue.testMode.enter(true);
});
`` - Introduction to Kue
- API walkthrough to Kue
We love contributions!
When contributing, follow the simple rules:
* Don't violate DRY principles.
* Boy Scout Rule needs to have been applied.
* Your code should look like all the other code – this project should look like it was written by one person, always.
* If you want to propose something – just create an issue and describe your question with as much description as you can.
* If you think you have some general improvement, consider creating a pull request with it.
* If you add new code, it should be covered by tests. No tests – no code.
* If you add a new feature, don't forget to update the documentation for it.
* If you find a bug (or at least you think it is a bug), create an issue with the library version and test case that we can run and see what are you talking about, or at least full steps by which we can reproduce it.
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