I am using Keystonejs to make a small app. I want to print out a message every second since the server starts, so I use node-cron to handle this task.
function(){
var CronJob = require('cron').CronJob;
new CronJob('* * * * * *', function() {
console.log('You will see this message every second');
}, null, true, 'America/Los_Angeles');
}
However, I don't know where I should put this code to make sure that when server starts, this function will be triggered.
Can you help me with this problem? Thank you in advance.
you can alter your lib/core/start.js file to also execute that callback
Related
I am building a hosting server with node.JS and mongoDB.
The server will be used for people to save their files remotely. But I do not want to keep unattended files on the server because it will be a waste of memory on the server.
So there are two things I wish to do :
Delete Files if not attended for more than 10 days
Leave the Files otherwise
Is there a way this can be done easily?
You can use cron job for this type of scheduled task. NodeJS has a module named cron to perform a scheduled task.
Approach:
Every day at midnight you will check for unattended files. If you find any unattended file then you can delete it.
Example code:
const CronJob = require('cron').CronJob;
new CronJob('0 0 * * *', async () => {
// Find files
// Delete files
}, null, true, 'America/Vancouver', null, false);
You can schedule a cron and it will check for your condition and do the desired action.
https://www.npmjs.com/package/cron
example:
var CronJob = require('cron').CronJob;
var job = new CronJob('* * * * * *', function() {
console.log('You will see this message every second');
}, null, true, 'America/Los_Angeles');
job.start();
I would like to do some cronjob using the Node.js package "cron" every 10 minutes.
This cronjob takes between 5 to 15 minutes, and I don't want that in a case that one instance is still running - another will be joining it in parallel. Instead, it will skip the additional running and wait until the next period.
Is it possible to implement it using this package?
Here is the code of the implementation using the cron package :
const CronJob = require("cron").CronJob;
const job = new CronJob(
'0 */10 * * * *',
()=>SomeCronJob(),
null,
true,
'America/Los_Angeles',
);
I thought of implementing it using a combination of simple setInterval() and clearInterval() instead of the package, not sure how though.
I'd appreciate any help!
I would use a flag to check if the job is running. Example:
let isJobRunning = false;
function SomeCronJob() {
if (isJobRunning) {
// Skip
return;
}
isJobRunning = true;
// run stuff
// Once is finished
isJobRunning = false;
}
is it possible to get cron to go into one of your scripts on the server and change a variable at a certain time?
cron simply fires a program/script at a given time. You would need an intermediate script/program to change the variable. But you could schedule a script to run that changes your variable.
You can install cron npm module to do it:
$ yarn add cron
And then in your code:
const CronJob = require('cron').CronJob;
let i = 0;
new CronJob('* * * * * *', function() {
console.log('You will see this message every second');
i++;
console.log(`Value of i = ${i}`);
}, null, true, 'America/Los_Angeles');
I have node application in which I want to run tasks on daily basis. So I want to use node-cron to schedule tasks but not like this:
var cron = require('node-cron');
cron.schedule('* * * * *', function(){
console.log('running a task every minute');
});
I need some generic solution so that at one place I have just empty body for cron job that takes different functions from a different location. That means in total we have two files, one which has just cron job function handler and other have a list of cron jobs. From where we want to run these jobs we just need require and some basic calling.
Can anyone suggest me this solution?
I got my solution. Using node-cron-job module I have achieved what I wanted. Let me explain in detail:-
First i created new file which contains jobs, lets name it jobs.js :-
// jobs.js
exports.first_job = {
on:"* * * * * " //runs every minute
},
job: function () {
console.log("first_job");
},
spawn: true
}
exports.second_job = {
on: "*/2 * * * * *", //runs every 2 second
job: function () {
console.log("second_job");
},
spawn: false // If false, the job will not run in a separate process.
}
Here, we define two jobs name first_job and second_job. We can define as many required.
Finally, we need to call these jobs from any location by these simple steps:-
// main.js
var cronjob = require('node-cron-job');
cronjob.setJobsPath(__dirname + '/jobs.js'); // Absolute path to the jobs module.
cronjob.startJob('first_job');
cronjob.startJob('second_job');
We can call all jobs in a single call like this:-
cronjob.startAllJobs();
I am running a cron job using the module node-cron for node js . My code is below.
var Job = new CronJob({
cronTime: '* * 01 * * *', //Execute at 1 am every day
onTick : function() {
co(function*() {
yield insertToDatabase(); //this is the function that does insert operation
}).catch(ex => {
console.log('error')
});
},
start : false,
timeZone: 'Asia/Kolkata'
});
I need to execute this only one time but this cronjob once starts runs multiple times due to which same data gets inserted to my database. I only need to run this job only one time. What should i do.
I know I am late to the party but I think that I have a solution. I hope this can help someone else in the future (Hi future!)
I encountered what I think to be the same issue as the asker, that is, the OnTick function executes multiple times after the scheduled time, this appeared to the author to be an endless loop. The asker expected this function to run only once at the scheduled time everyday (today, tomorrow, etc).
With that in mind the cause of this "issue" is simple. The cron job is scheduled to to exactly this. The cron time entered is * * 01 * * * which means the hour is 01 (aka 1:00am) but the minutes and seconds are *. This means any minute and any second where the hour is 01. So this will run from 1:00am up until 1:59am. It will run for each second of each minute until 2:00am. If the author had waited until 2:00am the "looping" would have ceased.
The solution is to set the seconds and minutes to anything that is not * (0 in my case worked).
I feel really silly for not having figured this out right away but here it is!
You can call Job.stop() from onTick:
onTick : function() {
Job.stop();
co(function*() {
yield insertToDatabase();
}).catch(ex => {
console.log('error');
});
}
In my case, i changed my code from this :
var job = new CronJob('*/59 * * * *', onTick, onComplete, true, 'Asia/Kolkata'); // onTick and onComplete is a function, which i'm not showing here
job.start();
To this :
var job = new CronJob('*/59 * * * *', onTick, onComplete, false, 'Asia/Kolkata'); // onTick and onComplete is a function, which i'm not showing here
job.start();
Thanks