pop-queue

Redis and Mongo backed light weight job queue

Install package via npm

npm i pop-queue

Pre-requisites:

1. MongoDB
2. Redis

The queue is maintained as redis array.

Concurrency is always 1. To run multiple simultaneous runners, fork with pm2. 10 sec idle time (gap between array pop) when no jobs are queued.

Lets start with creating an exporter file queue.js

import { PopQueue } from 'pop-queue';

const dbUrl = 'mongodb://localhost:27017';
const redis = {
    port: '6379',
    host: '127.0.0.1',
    password: '*******'
}
const dbName = 'pqueuedb' // default is circledb

export const popQueue = new PopQueue(
    dbUrl,
    redis,
    dbName,
    "pop_queues" // default collection name. Can be different for different runners
)

Now, lets create runner functions runner.js. Each runner pops a job by name and executes it.

import { popQueue } from './queue.js';

function runner1(job) {
    try {
        console.log("job 1 ran", job.data.name);
    } catch(err) {
        throw new Error("Error while running runner 1");
    }
}

function runner2(job) {
    try {
        console.log("job 2 ran", job.data.name);
    } catch(err) {
        throw new Error("Error while running runner 2");
    }
}

popQueue.define(
    "job1", // Runner name (unique)
    runner1
)
popQueue.define(
    "job2", // Runner name (unique)
    runner2
)

popQueue.connect().then(async (err) => {
    if(err) {
        throw err;
    }
    await popQueue.start();
})

Now we need a file to push jobs to queue scheduler.js. This is to emulate job addition is queue.

import { popQueue } from './queue.js';

setInterval(() => {
    let name = getJobName();
    popQueue.now(
        { name }, // data
        "job1"
    )
    console.log("Pushing job1", name);
}, 10 * 1000);

setInterval(() => {
    let name = getJobName();
    popQueue.now(
        { name }, // data
        "job2"
    )
    console.log("Pushing job2", name);
}, 8 * 1000);


function getJobName() {
    return "job_" + parseInt(Math.random() * 100)
}

Finally lets create an index.js file.

import * as runner from "./runner.js";
import * as scheduler from "./scheduler.js";

Run the index file to start pop-queue

node index.js