after DST scheduler is stuck, jobs are not getting fired

[vasukandimalla]

Things to check first

• I have checked that my issue does not already have a solution in the FAQ

• I have searched the existing issues and didn't find my bug already reported there

• I have checked that my bug is still present in the latest release

Version

3.11.0

What happened?

With the apscheduler's cron trigger, jobs are not triggered after the DST transition period.

How can we reproduce the bug?

Set System time to 30 seconds prior to DST transition period - 2025-03-09 01:59:30 AM

import asyncio
from datetime import datetime

from apscheduler.schedulers.asyncio import AsyncIOScheduler

import logging

logging.basicConfig(level=logging.DEBUG)
logger = logging.getLogger('apscheduler')
logger.setLevel(logging.DEBUG)


def tick():
    print(f"Tick! The time is: {datetime.now()}")


async def main():
    scheduler = AsyncIOScheduler()
    scheduler.add_job(tick, "cron", second="*/7")
    scheduler.start()
    while True:
        for job in scheduler.get_jobs():
            print(f"==== timestamp:{datetime.now()}, scheduler jobs ==> Job "
                  f"{job.id} scheduled next run at: {job.next_run_time}====")
        await asyncio.sleep(5)


if __name__ == "__main__":
    try:
        asyncio.run(main())
    except (KeyboardInterrupt, SystemExit):
        pass

execution output

DEBUG:asyncio:Using selector: KqueueSelector
DEBUG:tzlocal:/etc/localtime found
DEBUG:tzlocal:1 found:
 {'/etc/localtime is a symlink to': 'America/Chicago'}
INFO:apscheduler.scheduler:Adding job tentatively -- it will be properly scheduled when the scheduler starts
INFO:apscheduler.scheduler:Added job "tick" to job store "default"
INFO:apscheduler.scheduler:Scheduler started
DEBUG:apscheduler.scheduler:Looking for jobs to run
DEBUG:apscheduler.scheduler:Next wakeup is due at 2025-03-09 01:59:35-06:00 (in 3.099565 seconds)
==== timestamp:2025-03-09 01:59:31.900390, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 01:59:35-06:00====
DEBUG:apscheduler.scheduler:Looking for jobs to run
INFO:apscheduler.executors.default:Running job "tick (trigger: cron[second='*/7'], next run at: 2025-03-09 01:59:35 CST)" (scheduled at 2025-03-09 01:59:35-06:00)
INFO:apscheduler.executors.default:Job "tick (trigger: cron[second='*/7'], next run at: 2025-03-09 01:59:35 CST)" executed successfully
DEBUG:apscheduler.scheduler:Next wakeup is due at 2025-03-09 01:59:42-06:00 (in 6.994773 seconds)
Tick! The time is: 2025-03-09 01:59:35.004849
==== timestamp:2025-03-09 01:59:36.900796, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 01:59:42-06:00====
==== timestamp:2025-03-09 01:59:41.901411, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 01:59:42-06:00====
Tick! The time is: 2025-03-09 01:59:42.001396
DEBUG:apscheduler.scheduler:Looking for jobs to run
DEBUG:apscheduler.scheduler:Next wakeup is due at 2025-03-09 01:59:49-06:00 (in 6.999166 seconds)
INFO:apscheduler.executors.default:Running job "tick (trigger: cron[second='*/7'], next run at: 2025-03-09 01:59:49 CST)" (scheduled at 2025-03-09 01:59:42-06:00)
INFO:apscheduler.executors.default:Job "tick (trigger: cron[second='*/7'], next run at: 2025-03-09 01:59:49 CST)" executed successfully
==== timestamp:2025-03-09 01:59:46.902171, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 01:59:49-06:00====
DEBUG:apscheduler.scheduler:Looking for jobs to run
DEBUG:apscheduler.scheduler:Next wakeup is due at 2025-03-09 01:59:56-06:00 (in 6.998527 seconds)
INFO:apscheduler.executors.default:Running job "tick (trigger: cron[second='*/7'], next run at: 2025-03-09 01:59:56 CST)" (scheduled at 2025-03-09 01:59:49-06:00)
INFO:apscheduler.executors.default:Job "tick (trigger: cron[second='*/7'], next run at: 2025-03-09 01:59:56 CST)" executed successfully
Tick! The time is: 2025-03-09 01:59:49.001911
==== timestamp:2025-03-09 01:59:51.902916, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 01:59:56-06:00====
DEBUG:apscheduler.scheduler:Looking for jobs to run
DEBUG:apscheduler.scheduler:Next wakeup is due at 2025-03-09 03:00:00-05:00 (in 3603.999241 seconds)
INFO:apscheduler.executors.default:Running job "tick (trigger: cron[second='*/7'], next run at: 2025-03-09 03:00:00 CDT)" (scheduled at 2025-03-09 01:59:56-06:00)
INFO:apscheduler.executors.default:Job "tick (trigger: cron[second='*/7'], next run at: 2025-03-09 03:00:00 CDT)" executed successfully
Tick! The time is: 2025-03-09 01:59:56.001176
==== timestamp:2025-03-09 01:59:56.903779, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 03:00:00-05:00====
==== timestamp:2025-03-09 03:00:01.904669, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 03:00:00-05:00====
==== timestamp:2025-03-09 03:00:06.905596, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 03:00:00-05:00====
==== timestamp:2025-03-09 03:00:11.906636, scheduler jobs ==> Job cc015b86296049cb8bdf58909341dcf1 scheduled next run at: 2025-03-09 03:00:00-05:00====

[agronholm]

The problem has been fixed in master but that was for the refactored cron trigger that uses ZoneInfo timezones instead of pytz ones. Attempts have been made to port the fix over to v3.x, but they were unsuccessful.