NodeJs scheduling jobs on multiple nodes - node.js

Question

I have two nodeJs servers running behind a Load Balancer. I have some scheduled jobs that i want to run only once on any of the two instances in a distributed manner.
Which module should i use ? Will node-quartz(https://www.npmjs.com/package/node-quartz) be useful for this ?

Answer 1

Adding redis and using node-redlock seemed like overkill for the little caching job I needed to schedule for once a day on a single server with three Node.js processes behind a load balancer.
I discovered http://kvz.io/blog/2012/12/31/lock-your-cronjobs/ - and that led me to the concept behind Tim Kay's solo.
The concept goes like this - instead of locking on an object (only works in a single process) or using a distributed lock (needed for multiple servers), "lock" by listening on a port. All the processes on the server share the same ports. And if the process fails, it will (of course) release the port.
Note that hard-failing (no catch anywhere surrounding) or releasing the lock in catch are both OK, but neglecting to release the lock when catching exceptions around the critical section will mean that the scheduled job never executes until the locking process gets recycled for some other reason.
I'll update when I've tried to implement this.
Edit
Here's my working example of locking on a port:
multiProc.js
var net = require('net');
var server = net.createServer();
server.on('error', function () { console.log('I am process number two!'); });
server.listen({ port: 3000 },
function () { console.log('I am process number one!');
setTimeout(function () {server.close()}, 3000); });
If I run this twice within 3 seconds, here's the output from the first and second instances
first
I am process number one!
second
I am process number two!
If, on the other hand, more than 3 seconds pass between executing the two instances, both claim to be process number one.

Answer 2

I haven't done this before but I can see myself doing it this way.
Using any scheduler library for Node.js.
In order to achieve your goal, i would use redis for distributed lock. Before running any scheduled jobs, a worker / node will have to get the lock; do the job; and release / ack() when finishing the job (or on error).

Answer 3

A single server can be selected a leader by conducting a election among available instances using Zoologist package
https://www.npmjs.com/package/zoologist
Requires Zookeeper server to conduct the election

Answer 4

I don't know if this might help you, but still posting it here.
Usually node-schedule is used for time based schedules where you have to execute arbitrary code only once. For eg: a database read/write on next month 6:00 PM.

Answer 5

The following post will explain writing the scheduled Jobs which will perform certain action based on our requirement for a particular time / day instance.
For performing the above task we are going to use CRON package of node.
To add a job we need to :
1) Install Cron
npm install cron
2) Require cron 's CronJob to our project.
var CronJob = require('cron').CronJob
3) Create an instance of CronJob
var jobs = new CronJob({
cronTime: ' * * * * * *',
onTick: function () {
//perform Your action
},
start: false,
timeZone: 'Asia/Kolkata'
});
Arguments
cronTime: it takes 6 arguments namely :
1) Second - > 0 - 59
2) Minute - > 0 - 59
3) Hour - > 0 - 23
4) Day of Month - > 1 - 31
5) Months - > 0 - 11
6) Day of Week - > 0 - 6
Note: We Can define cronTime in ranges alse like * for always.
0 - 59 / 5 at every 5 minute.
onTick: The operation to perform.
Start: It takes a boolean and if true then starts the job now.
timeZone: job's timeZone
4) To start Job
jobs.start()
For Example :
var jobs = new CronJob({
cronTime: ' 00 00 0-23 * * *',
onTick: function () {
printMyName();
},
start: false,
timeZone: 'Asia/Kolkata'
});
jobs.start();
var printMyName = function () {
var date = new Date();
console.log("Hi Vipul it is ", today);
};
Hope it helps.