I've been working with node for the first time in a while again and stumbled upon node-schedule, which for the most part has been a breeze, however, I've found resuming a scheduled task after canceling it via job.cancel() pretty difficult.
For the record, I'm using schedule to perform specific actions at a specific date (non-recurring) and under some circumstances cancel the task at a specific date but would later like to resume it.
I tried using job.cancel(true) after cancelling it via plain job.cancel() first as the documentation states that that would reschedule the task, but this has not worked for me. Using job.reschedule() after having cancelled job first yields the same result.
I could probably come up with an unelegant solution, but I thought I'd ask if anyone knows of an elegant one first.
It took me a while to understand node-schedule documentation ^^
To un-cancel a job, You have to give to reschedule some options.
If you don't pass anything to reschedule, this function returns false (Error occured)
For exemple, you can declare options, and pass this variable like this :
const schedule = require('node-schedule');
let options = {rule: '*/1 * * * * *'}; // Declare schedule rules
let job = schedule.scheduleJob(options, () => {
console.log('Job processing !');
});
job.cancel(); // Cancel Job
job.reschedule(options); // Reschedule Job
Hope it helps.
Related
I am very new to NodeJS and trying to develop an application which acts as a scheduler that tries to fetch data from ELK and sends the processed data to another ELK. I am able to achieve the expected behaviour but after completing all the processes, scheduler job does not exists and wait for another scheduler job to come up.
Note: This scheduler runs every 3 minutes.
job.js
const self = module.exports = {
async schedule() {
if (process.env.SCHEDULER == "MinuteFrequency") {
var timenow = moment().seconds(0).milliseconds(0).valueOf();
var endtime = timenow - 60000;
var starttime = endtime - 60000 * 3;
//sendData is an async method
reports.sendData(starttime, endtime, "SCHEDULER");
}
}
}
I tried various solutions such Promise.allSettled(....., Promise.resolve(true), etc, but not able to fix this.
As per my requirement, I want the scheduler to complete and process and exit so that I can save some resources as I am planning to deploy the application using Kubernetes cronjobs.
When all your work is done, you can call process.exit() to cause your application to exit.
In this particular code, you may need to know when reports.sendData() is actually done before exiting. We would have to know what that code is and/or see the code to know how to know when it is done. Just because it's an async function doesn't mean it's written properly to return a promise that resolves when it's done. If you want further help, show us the code for sendData() and any code that it calls too.
I wanted to perform some data processing in parallel using Bull NPM and start processing each job at the given cron Time
const Queue = require("bull"),
/**
* initialize the queue for executing cron jobs
**/
this.workQueue = new Queue(this.queueOptions.name, {
redis: redisConfig
});
this.workQueue.process((job, done) => {
done();
this.processJob(job)
.then(data => {
global.logger.info(`successfully-executed-job ${job.id}`);
})
.catch(error => {
global.logger.error(`JSON.stringify(error)}-in-executing-job-${job.id}`);
});
});
// here I have included Unique JobId
this.workQueue.add({}, {repeat: { cron:"5 * * * *",jobId:Date.now()});
Any suggestions to achieve the same?
The issue is resolved now if you're facing the same issue make sure that you're referring to the correct timezone.
Cheers!!
I also faced this same issue. One thing to note with respect to the above code is that a Queuescheduler instance is not initialized. Ofcourse timezone also plays a crucial role. But without a Queuescheduler instance (which has the same name as the Queue), the jobs doesnt get added into the queue. The Queuescheduler instance acts as a book keeper. Also take care about one more important parameter "limit". If you dont set the limit to 1, then the job which is scheduled at a particular time will get triggered unlimited number of times.
For example: To run a job at german time 22:30 every day the configuration would look like:
repeat: {
cron: '* 30 22 * * *',
offset: datetime.getTimezoneOffset(),
tz: 'Europe/Berlin',
limit: 1
}
Reference: https://docs.bullmq.io/guide/queuescheduler In this above link, the documentation clearly mentions that the queuescheduler instance does the book keeping of the jobs.
In this link - https://docs.bullmq.io/guide/jobs/repeatable, the documentation specifically warns us to ensure that we instantiate a Queuescheduler instance.
I have a list of URLs in DB. I want to periodically check if those URLs are alive or not.
So I create a long running service which run infinite loop, each iteration:
Query database to get list of urls
For each URL, make request to check if it is alive or not
Please guide me how to implement that service.
I looked at Bull and Kue, but they seem not support infinite loop service?
You can use something very simple like setInterval() to have your task repeat x amount of times.
var testUrls = function(){
//do your magic of connecting to the DB and checking urls.
}
setInterval(testUrls, 60000);
The above code snippet will call your function testUrls every minute.
Or if you need more control over the scheduling you can use a npm package like cron.
You can use node-schedule
Its very simple
var schedule = require('node-schedule');
var j = schedule.scheduleJob('42 * * * *', function(){
console.log('The answer to life, the universe, and everything!');
});
Does anyone know if it's possible to make a Heroku Scheduler job that would send an email to all of my users once per day? I'm using Meteor and MongoDB.
I can see that the Heroku Scheduler can run a command such as "node somefile.js" but I can't seem to figure out how to make a connection to the mongodb in a file like this. Can I somehow tap into the DB without involving Meteor in this?
Any help would be appreciated!
I eventually found a package to do so: synced-cron. Basically, you need to setup a method in which use the package to fire a recurring job.
The package website also has a sample code:
SyncedCron.add({
name: 'Crunch some important numbers for the marketing department',
schedule: function(parser) {
// parser is a later.parse object
return parser.text('every 2 hours');
},
job: function() {
var numbersCrunched = CrushSomeNumbers();
return numbersCrunched;
}
});
Here you just need to replace the code in the job function to send out the email.
The job supports schedules like "every 5 minutes", "at 5:00pm", etc. The package relies on the text parser in Later.js to parse the schedule. You can refer to the Later.js doc.
Two different options.
The first is to use Heroku's scheduler,
In which you create a text file in your bin directory:
#! /app/.heroku/node/bin/node
var test = require('./jobToDo') //put your job in this file (jobToDo.js)
Now you don't have to put the job in another .js file, but it makes it easier to work with, rather than coding in a plain text file. (put again that is up to you)
The first line #! /app/.heroku/node/bin/node may be different for you depending on how your configuration is set up, depending on your OS and node/npm set up.
The second option is a cron style library. This will allow you to decide when you want your code to run.
This is pretty easy, and for me the preferred method.
var CronJob = require('cron').CronJob;
var fn = function(){
// Do Something
}
var job = new CronJob({
cronTime: "00 00 02 * * 1-5",
onTick: fn,
start: true,
timeZone: 'America/Los_Angeles'
});
You can look at documentation on github
I have a list on which I have an ItemUpdated handler.
When I edit using the datasheet view and modify every item, the ItemUpdated event will obviously run for every single item.
In my ItemUpdated event, I want it to check if there is a Timer Job scheduled to run. If there is, then extend the SPOneTimeSchedule schedule of this job to delay it by 5 seconds. If there isn't, then create the Timer Job and schedule it for 5 seconds from now.
I've tried looking to see if the job definition exists in the handler and if it does exist, then extend the schedule by 5 seconds. If it doesn't exist, then create the job definition to run in a minutes time.
MyTimerJob rollupJob = null;
foreach (SPJobDefinition job in web.Site.WebApplication.JobDefinitions)
{
if (job.Name == Constants.JOB_ROLLUP_NAME)
{
rollupJob = (MyTimerJob)job;
}
}
if (rollupJob == null)
{
rollupJob = new MyTimerJob(Constants.JOB_ROLLUP_NAME, web.Site.WebApplication);
}
SPOneTimeSchedule schedule = new SPOneTimeSchedule(DateTime.Now.AddSeconds(5));
rollupJob.Schedule = schedule;
rollupJob.Update();
When I try this out on the server, I get a lot of errors
"An update conflict has occurred, and you must re-try this action. The object MyTimerJob Name=MyTimerJobName Parent=SPWebApplication Name=SharePoint -80 is being updated by NT AUTHORITY\NETWORK SERVICE in the w3wp process
I think the job is probably running for the first time and once running, the other ItemUpdated events are coming in and finding the existing Job definition. It then tries to Update this definition even though it is currently being used. Should I make a new Job Definition name so that it doesn't step on top of the first? Or raise the time to a minute?
I solved this myself by just setting the delay to a minutes time from now regardless of whether a definition is found. This way, while it is busy, it will keep pushing back the scheduling of the job until it is done processing
This is because the event is asynchronous. You'll need to rethink exactly what you're trying to solve with this code and potentially re-factor it.
Maybe you should try using "lock" on the timer job object?