looking for a node.js scheduler that wont start if the job is still running

Question

I'm looking for a schedular/ cron for nodejs. But I need an important feature- if the jobs did not finish (when the time for it to start again arrived), I want it to not start/ delay the schedule. For example, I need to run a job every 5 minutes. The job started at 8:00, but finished only at 8:06. so I want the job of 8:05 to either wait until 8:06, or not to start at all, and wait for the next cycle at 8:10. Is there a package that does that? If not, what is the best way to implement this?

Answer 1

You can use the cron package. It allows you to start/stop the cronjob manually. Which means you can call these functions when your cronjob is finished.

const CronJob = require('cron').CronJob;
let job;

// The function you are running
const someFunction = () => {
    job.stop();

    doSomething(() => {
        // When you are done
        job.start();
    })
};

// Create new cronjob
job = new CronJob({
    cronTime: '00 00 1 * * *',
    onTick: someFunction,
    start: false,
    timeZone: 'America/Los_Angeles'
});

// Auto start your cronjob
job.start();