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A distributed work queue for node.js based on redis and RxJS.

Overview

'qrx' provides reactive work queue implemented with redis and RxJS. The goals of the project:

• Distributed: Enable shared asynchronous compute resources on top a native node.js technology stack.
• Focus on minimalism
• Ease of installation (redis and on node are easy)
• Practical performance: Approach near raw redis performance levels with queuing primitives
• Leverage Reactive combinator abstraction for modeling asynchronous distributed computing
• Fully asynchronous semantics

Installation

npm install qrx

Prerequisites

qrx requires a redis installation see: http://redis.io/download

npm install

[sudo] npm install qrx

Features

• Easily create a queue with name
• Enable async compute resource using Rx primatives
• Cluster support
• Leverage redis high performance pub/sub

Usage

###Simple usage with 1 queue instance

(From: /examples/hello-qrx.js)

// create a new queue with well known name
wq = new WorkQueueRx();
// clear any pending work (optional)
wq.clear();

wq.enqueue('one');
wq.enqueue('two');

// subscribe for work
wq.workObservable().Subscribe(function(workObj){
  console.log('new work', workObj.work);
  // callback to mark the work completed or err'd
  workObj.callback(null, workObj.work + ' - completed');
});

// subscribe for completed work
wq.completedObservable().Subscribe(function(completedWork){
  console.log('completed work', completedWork)
})

1 Master/Multiple Slaves

(From: /test/qrx-test.js)

var wqMaster = new WorkQueueRx({qname: 'clean-test2'});

var WORK_COUNT = 500;

console.log('Test WorkCount', WORK_COUNT);
for(var i=0; i < WORK_COUNT; i++){
  wqMaster.enqueue(i);
}

// two slaves serving 1 master
var workReceived = 0;
var slave1 = new WorkQueueRx({qname: 'clean-test2'});
slave1.workObservable().Subscribe(function(workObj){
  workReceived++;
  workObj.callback(null, workObj.work + 3);
});

var slave2 = new WorkQueueRx({qname: 'clean-test2'});
slave2.workObservable().Subscribe(function(workObj){
  workReceived++;
  workObj.callback(null, workObj.work + 3);
});

// master get's his work
var completedWorkCount = 0;
wqMaster.completedObservable().Subscribe(function(workItem){
  completedWorkCount++;
  console.log('Completed Work', workItem.completedWork);
})
  

ForkMany combinator extension to Rx

(From: /examples/fork-many.js)

Rx.Observable.FromArray([1,2,3])
  // ForkMany usage
  .ForkMany({qname: 'test-q'})
    .Subscribe(function(result){
      console.log(result);
    });

var worker = new WorkQueueRx({qname: 'test-q'});
worker.workObservable().Subscribe(function(workItem){
  workItem.callback(null, workItem.work + 1);
});

ToDo

• Work stop singals
• Enable transactional queueing using redis primatives
• Performance optimization
  • Refactor to remove SelectMany and borrow timeline from message notification
  • Investigage why redis client is holding only memory
• Flood control on queue restarts
• Add semantics for repeated work sent to workers, where the work doesn't callback
• Add support for asynchronous work subscribers with incremental results
• Add JoinMany operator to re-sequence completed with (with timeout)
• Add queue management and monitoring UI
  • Pub/Sub for worker monitoring
  • Rickshaw + socket.io for realtime graphs
• Add timeout semantics for jobs

License

Copyright (c) Loku. All rights reserved. The use and
distribution terms for this software are covered by the Eclipse
Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
which can be found in the file epl-v10.html at the root of this
distribution. By using this software in any fashion, you are
agreeing to be bound by the terms of this license. You must
not remove this notice, or any other, from this software.