Missing Cron Execution during DST change

[ishan393]

Description

Hi, thanks to author and everyone contributing for making this amazing library possible.

Encountered an issue where the cron jobs aren't triggering during daylight saving change.

For example: TimeZone - Australia/Melbourne 7 Apr 2024 - Daylight savings time ended and clocks turned back 1 hour
Time goes from 2:59 -> 2:00 (See example below)

Expected Behavior

The Cron job should trigger every half an hour (See example below)

Actual Behavior

The Cron job didn't trigger for one hour and missed two executions. Missing cron job executed log two times (See example below)

Steps to Reproduce

const { CronJob } = require("cron");
const fakeTImers = require("@sinonjs/fake-timers");

process.env.TZ = "Australia/Melbourne";

const main = () => {
  const clock = fakeTImers.install({
    now: new Date("2024-04-07T01:00:00.000"),
  });
  const job = new CronJob(
    "*/30 * * * *", // every 30 minutes
    function () {
      console.log(
        "Cron job executed. The current time is: ",
        new Date().toString()
      );
    },
    null,
    true,
    "Australia/Melbourne"
  );

  console.log("current time is: ", new Date().toString());
  console.log("Going to advance time by 30 minutes");
  clock.tick(1000 * 60 * 30);
  console.log("Time after advancing is ", new Date().toString());
  console.log("\n");

  console.log("current time is: ", new Date().toString());
  console.log("Going to advance time by 30 minutes");
  clock.tick(1000 * 60 * 30);
  console.log("Time after advancing is ", new Date().toString());
  console.log("\n");

  console.log("current time is: ", new Date().toString());
  console.log("Going to advance time by 30 minutes");
  clock.tick(1000 * 60 * 30);
  console.log("Time after advancing is ", new Date().toString());
  console.log("\n");

  console.log("current time is: ", new Date().toString());
  console.log("Going to advance time by 30 minutes");
  clock.tick(1000 * 60 * 30);
  console.log("Time after advancing is ", new Date().toString());
  console.log("\n");

  console.log("current time is: ", new Date().toString());
  console.log("Going to advance time by 30 minutes");
  clock.tick(1000 * 60 * 30);
  console.log("Time after advancing is ", new Date().toString());
  console.log("\n");

  console.log("current time is: ", new Date().toString());
  console.log("Going to advance time by 30 minutes");
  clock.tick(1000 * 60 * 30);
  console.log("Time after advancing is ", new Date().toString());
  console.log("\n");

  console.log("current time is: ", new Date().toString());
  console.log("Going to advance time by 30 minutes");
  clock.tick(1000 * 60 * 30);
  console.log("Time after advancing is ", new Date().toString());
  console.log("\n");
};

main();

Output:

current time is:  Sun Apr 07 2024 01:00:00 GMT+1100 (Australian Eastern Daylight Time)
Going to advance time by 30 minutes
Cron job executed. The current time is:  Sun Apr 07 2024 01:30:00 GMT+1100 (Australian Eastern Daylight Time)
Time after advancing is  Sun Apr 07 2024 01:30:00 GMT+1100 (Australian Eastern Daylight Time)


current time is:  Sun Apr 07 2024 01:30:00 GMT+1100 (Australian Eastern Daylight Time)
Going to advance time by 30 minutes
Cron job executed. The current time is:  Sun Apr 07 2024 02:00:00 GMT+1100 (Australian Eastern Daylight Time)
Time after advancing is  Sun Apr 07 2024 02:00:00 GMT+1100 (Australian Eastern Daylight Time)


current time is:  Sun Apr 07 2024 02:00:00 GMT+1100 (Australian Eastern Daylight Time)
Going to advance time by 30 minutes
Cron job executed. The current time is:  Sun Apr 07 2024 02:30:00 GMT+1100 (Australian Eastern Daylight Time)
Time after advancing is  Sun Apr 07 2024 02:30:00 GMT+1100 (Australian Eastern Daylight Time)


current time is:  Sun Apr 07 2024 02:30:00 GMT+1100 (Australian Eastern Daylight Time)
Going to advance time by 30 minutes
Time after advancing is  Sun Apr 07 2024 02:00:00 GMT+1000 (Australian Eastern Standard Time)


current time is:  Sun Apr 07 2024 02:00:00 GMT+1000 (Australian Eastern Standard Time)
Going to advance time by 30 minutes
Time after advancing is  Sun Apr 07 2024 02:30:00 GMT+1000 (Australian Eastern Standard Time)


current time is:  Sun Apr 07 2024 02:30:00 GMT+1000 (Australian Eastern Standard Time)
Going to advance time by 30 minutes
Cron job executed. The current time is:  Sun Apr 07 2024 03:00:00 GMT+1000 (Australian Eastern Standard Time)
Time after advancing is  Sun Apr 07 2024 03:00:00 GMT+1000 (Australian Eastern Standard Time)


current time is:  Sun Apr 07 2024 03:00:00 GMT+1000 (Australian Eastern Standard Time)
Going to advance time by 30 minutes
Cron job executed. The current time is:  Sun Apr 07 2024 03:30:00 GMT+1000 (Australian Eastern Standard Time)
Time after advancing is  Sun Apr 07 2024 03:30:00 GMT+1000 (Australian Eastern Standard Time)

Your Environment

• cron version: 3.1.7
• NodeJS version: 14.17.6
• Operating System and version: Ubuntu 16.04
• TypeScript version (if applicable):
• Link to your project (if applicable):

Might be related to: #563 #638

[sheerlox]

Hi, thanks for reporting and providing a reproduction means.

I took note of the issue and will try to dedicate some time to it when possible.

[edwhittle]

Hi @sheerlox - Is there a chance this could be picked up in the new year? The issue will re-occur on the 6th April 2025

[intcreator]

I'll look into it more. currently this repo is maintained by mostly me and Sheerlox though, all in our spare time, so we welcome outside help to address this issue! please consider opening a PR if you think you have a fix

[sheerlox]

I was hoping this would be fixed by #938, but unfortunately no. Posting the test case here for later:

// https://github.com/kelektiv/node-cron/issues/881
it('should not skip executions in Melbourne DST backward jump', () => {
	const d = DateTime.fromISO('2024-04-07T02:59:00', {
		zone: 'Australia/Melbourne'
	}).toJSDate();
	const clock = sinon.useFakeTimers(d.getTime());

	console.debug({ d });

	const job = new CronJob(
		'*/30 * 7 4 *',
		callback,
		null,
		true,
		'Australia/Melbourne'
	);

	const oneHour = 60 * 60 * 1000;
	clock.tick(oneHour);
	expect(callback).toHaveBeenCalledTimes(2);

	clock.restore();
	job.stop();
});