Kue: best practice for continuously processing/polling the queue

Question

What is the best way to continuously process items added to the queue? I see the following method

queue.process

https://github.com/Automattic/kue#processing-jobs

but this will process and return. Items added after this call are obviously not processed.

I thought to do:

queue.on('job enqueue', function(id, type){
            queue.process('email', function (job, done) {
                console.log('processing one: ' + job.id);
                done(null);
            });
        });

But not sure if this fires multiple process methods ignoring the current queue status?

EDIT:

I have created a handler to listen to the 'email' type, yet it is only called once given the scenario below. Unless I am missing something, I would expect process to be run exactly 10 times here?

const queue = kue.createQueue();

        queue.process('email', function (job, done) {
            email(job.id, job.data, done);
        });

        var email = function(id, email, done) {
          console.log('job: %s, sent to: %s number: %s', id, email.to, email.number);
          done(null, {result: 'OK'});
        };

        queue
            .on('job enqueue', function (id, type) {
                console.log('job %s got queued of type %s with id %s', id, type);
            })
            .on('job complete', function (id, result) {
                console.log('job complete: ' + id);
            });

        for (var i = 0; i < 10; i++) {
            queue
                .create('email', {
                    title: 'welcome email for tj',
                    number: i,
                    to: 'tj@learnboost.com',
                    template: 'welcome-email'
                })
                .removeOnComplete(true)
                .save();
        }

Answer 1

The function passed to queue.process will get called for each enqueued job.

Think of it as an event handler: it "listens" for (in this case) "email" events/jobs, and for each one the handler function will be called. So it's incorrect that "items added after this call are obviously not processed".

As per the fine manual, "by default a call to queue.process() will only accept one job at a time for processing", but you can increase the concurrency:

queue.process('email', 20, function(job, done){
  // ...
});

Some example code that shows the handler gets called for each new job:

const kue   = require('kue');
const queue = kue.createQueue();

queue.process('email', function(job, done){
  console.log('got job', job.data);
  done();
});

setInterval(() => {
  queue.create('email', {
    timestamp : new Date()
  }).save();
}, 1000);